Thanks, Guilford Guy.
  Thanks, Jim Banner, for the detailed help from your experience.  I thought I could plug my Walthers power pack into the E-Z command (using it as the power source), but not plug the Walthers into an electrical socket.  I was told I could plug my DC power pack into a Digitrax Zephyr.  I'm don't know whether my DC locomotive would then be run by E-Z Command or I would still use the control on the Walters power pack.   I see I'd have to use the two transformers separately, if I wanted the Walthers' AC output to power an accessory.
  At present, all I'd like a DCC control to do is run 2 trains for direction & speed & blow the horn, if my locomotive has sound.

 Thanks Woody Elmore.
  Jim Banner, if you've been modelling since the '50s, you must be in my generation.  My parents bought me a Marx all metal set in about 1950 & later a nicer Marx set with automatic couplers & many accessories.  I have finally started a scale model layout.
  Your detailed information is very helpful, & I will print it out.  The train person at the hobby shop I visited advised not to mix steel with nickel-silver.  She didn't say why (aesthetics?).  Your experience shows I can surround my initial oval of steel with an oval of nickel-silver.  I was starting to worry that my steel track would soon oxidize & not conduct.

 I just read this on the NMRA website:
"You might also consider rubbing the rails lightly with, believe it or not, hair clipper oil or another light oil that is plastic compatible. The Wahl brand is the modeler's favorite and it is available at some hobby shops or through barbers supply houses. It inhibits oxidation and improves contact. An article about this was in the June, 1981, RMC"
I wonder if I should do this to my Power-Loc steel alloy track.

 Thanks for your comments.  I have a Spectrum SD-45 with DCC for my freight train & a Walthers F7 DC for my passenger train (which I will replace with a better locomotive someday).  I looked up the manual for E-Z Command online & saw that it can run both trains & I can plug my DC power pack into the E-Z DCC.  I have a 38' oval layout.  I plan to add a concentric oval in order to run both trains simultaneously.  I want to connect them with a right & left switch for the option of running one on both ovals.
My wife is generous, but even she is beginning to exclaim at the money I'm spending just to get started.    All I want to do is run two trains & "hear that lonesome whistle blow."
  I can't find Model Railroad News here, but I just signed up at their website for 3 free issues.

Jhanecker2 & Santa Fe Buff,
  Thanks for the information.  I could get the E-Z straight terminal & use Power-Loc adapters.  I think I saw on eBay that Power-Loc has 3" sections. which might balance out adapters.

 The train person at the "local" (60 miles round-trip) hobby shop tried to sell me Digitrax Zephyr "entry level" DCC.  DCC seemed very complicated & the price of $180 made me gulp.  HO Scale Model Railroading recommends wiring it at least every 3'!  Reading recently here about Bachmann's E-Z Command Control, which costs less than half Digitrax, & now having a DCC locomotive, I am reconsidering.
  Does Plug & Play mean that I could plug the E-Z C C into the Power-Loc terminal track where my DC power pack is presently connected?
  If I could get sound installed in my Spectrum SD-45, would the DCC enable me to honk the horn when I want?  I heard the Union Pacific go by 3 times today, honking. 

ajp3751,
  Yes, my power supply came with the Walthers train set.  After reading here about Bachmann's E-Z Command Control as Plug & Play & costing less than half the Digitraz Zephyr "entry level" DCC that the train person at the hobby shop tried to sell me, I am interested in getting DCC, instead of a more powerful DC transformer.

 Thanks for all of the suggestions.  I'll print them out.  I don't understand why one can't get straight Power-Loc track with terminals.  What is the point of putting them only on 18" radius curved track?  Why not on 22" radius curved track?  Maybe Walthers has a suggestion box.  If EZ track had straight track with terminals, I could use Power-Loc adapters to integrate it.

ajp3751,
  My power supply is 7VA Maximum output, so I wonder if a 16 0r 17 VA maximum output power supply would speed up my SD-45.  I hadn't considered that it might be scaled down to "scale speed."  Does this look correct:  Bachmann Spectrum SD-45 travels 6612' HO scale feet (2 laps on my layout) a minute, times 60 = 396,720' an hour / 5280 = 75 scale mph!  It certainly doesn't seem to be travelling that fast!  It doesn't travel much faster all by itself at full throttle, while the Walters F7 would careen off the track.
  Jhanecker2,
  Last evening, I watched 2 Union Pacific locomotives moving cars, apparently to a siding, so that seems to be the railroad we have in West-Central Wisconsin.  I'm originally from northern Minnesota, so I feel nostalgic about the Great Northern.

  I got an excellent price on this locomotive in the railroad & era I wanted.  It arrived today.  It looks beautiful.  However, it pulls my 11 cars (with freight) only half as fast as the cheap Walthers F7 (4-wheel drive) that came with my train set!  The Walthers takes 16 seconds for a lap around my 38' DC track at 4/5 speed on the 7 VA power pack.  The Bachmann takes 30 seconds at full throttle!  Why is this?  Do I need a more powerful power pack?

Santa Fe Buff,

  I have a 6.5' x 13' layout with a lot of straight track.  I just haven't found straight terminal track.

Trainmanchirs,

  I would like to use 9" straight terminal track, if I could find it in PowerLoc.  I haven't done any drilling & wiring.

I currently have my power pack connected to an 18" Radius Curved Terminal Rerailer with Hook up Wire.  I am considering a concentric layout requiring 22" radius Power-Loc track to encompass the 18" radius layout, enabling me to run two trains on the separate ovals, but I can't find 22" radius Curved Terminal Rerailer with Hook up Wire.   How could I connect a power pack to the outer oval without using 18" radius curved terminal rerailer with hook up wire?

   Guilford Guy, I am interested in the '50s & '60s in Northern Minnesota, & am seeking a Great Northern locomotive, the kind I used to see pulling long lines of iron ore cars, besides boxcars (GN, SOOLine), & etc.  I just got 3 Bachmann DM&IR ore cars.  I am considering Athearn HO 94160 RTR GP35, GN/Sky #3038 http://www.modeltrainstuff.com/product_p/ath-94160.htm although I recall the GN's as orange & green.  I don't want to pay much more than this model's $65.
  Thanks for the help on power packs.  I was looking at an MRC1370 18VA for $30.  I'll have to read about DCC.  It seems complicated.
  I was wondering about weight's effect on traction.  The F7 that came with my Walthers set has only 4-wheel drive but pulls 9 cars with freight adequately.  If I got a diesel freight locomotive, I'd use the F7 for passenger cars.
 

 Thanks, SteamGene & Woody Elmore, for relieving my concern about couplers.  I was confused when I read that some are magnetic knuckle couplers, because mine are plastic.  I tried to copy a picture of my couplers here but can't seem to do it.
  Thanks, Jhanecker2.  I found an adapter at Walthers' website (which is difficult to search) but haven't ordered any yet.  If they add to the length of the track & I'd need 2 to place EZ track between Power-Loc, then I'd need 2 on the other side of my layout to make it equal in length.
  The transformer that came with my train set says Maximum Output 7 VA.  It has 5 marks for forward & 5 for backward. I haven't yet found information about what transformer a more powerful locomotive would need.