Thanks again to all -- the advice has been excellent.  I probably wouldn't hesitate in completely switching the layout to a permanent DCC configuration, except for the fact that many of those inefficient old engines were puchased for me by my father over many birthdays and Christmases when I was very young, and have great senimental value. I'd hate to just put them up on a shelf.
I'm thinking out loud here -- but considering how easy it is switching from one configuration to another (as you all have shown me) -- I think it may be possible to have one master switch, which would change the entire layout from DC to DCC and back.  It just would require a complete changeout of engines and carefully repositioning all power switches prior to applying the master power switch...I'll have to do a little more research...

Thanks for all the advice everyone.  I'll research all the good tips, and see what direction things take me.  The reason I was reluctant to convert the system to DCC from DC was the work I thought it involved.
For example, there are insulating plastic rail-joiners everywhere that I assumed would need to come out.  The rails have already been landscaped with loose scale bedding, and it would just make a mess.  Secondly, I have about seven or eight DC locomotives (Tyco, Bachman, Atlas, to name a few) that would all have to be converted. I'm fairly handy with a soldering gun, but I think it would get a little cost prohibitive, and no two engines seem the same -- I'd need to do a lot of conversion research.  Finally, this was the system was the one that I built with my dad, and I'm a little reluctant to do renovations - the less change the better...but then again, maybe my dad would've gotten a kick out of al that DCC has to offer -- thanks once again...Jack

Hi folks, I have an old 4'x8' layout that I constructed with my dad as a youngster over 40 years ago. This setup is a pretty well established -- run by a DC powerpack with tons of wiring.  My dad passed away this past summer and am trying to get the railroad up and running again.
I've never had a steam locomotive and was thinking of purchasing a Bachmann Baldwin 2-8-0 in Nickel Plate Road markings in honor of my grandfather, who worked for that company many years ago.
I think I've figured out the basics of a DCC system, and with all my old equipment, at this point a conversion/modification just wouldn't be practical.
My questions are about the basics of operating a DCC/DC train on a DC only system.  Are there any gotchas I need to be aware of?  Are there any drawbacks?  How do all the "Bells and Whistles" (sound effects) etc. work on the DC only system? Thanks in advance... Jack