Thank you all for your input.  I greatly appreciate it.  Looks like I am going to have to find some space indoors or drop a whole lot of money to get a G scale train set up (something "She Who Must Be Obeyed" will not like). 

Cost for G scale trains is an issue, at least from what I have seen online and at specialty stores.  EBay has single engines (not the whole train or track, just the engine) starting around $250 a pop.  Rolling stock isn't too bad, but the engine and the track is just prohibitively expensive (of course, I could ask my kids not to eat for a couple of months and that would solve the problem!!!   ).  I went to a specialty store and priced a full startup set - $1,200.  Granted, that was for an oval track with the Walt Disney World (or Disneyland) Railroad, but the other sets were similarly priced (that one just sticks in my mind - sticker shock).

I don't have a basement, but I do have an entertainment room separate from the rest of the house.  There is not a whole lot of space, but I may be able to move thjings around a bit to make things fit and have an HO setup (albeit considerably smaller than I would envision and that does not accomodate the trains I have).  I will pull out the measuring tape and see what I can work out.

As an aside, does anyone know of a good site to purchase used G gauge trains and track?  It has to be cheaper than buying new.

Again, thank you all for your help.

I have heard several opinions online and via e-mail lately regarding the use of HO trains and track for outdoor use.  Previously, I was under the impression that you could only use HO indoors and that you could only use G trains outdoors, but statements made in some advertisements and to some model railroad manufacturers seem to indicate otherwise. 

Bachmann said that all of their equipment is suitable for outdoor use, except its G track.  To say the least, the statement completely baffled me (how can the trains be okay for outdoor use, but not the track?   ).

My wife (aka "She Who Must Be Obeyed" -  ) finally relented and agreed that an area of our backyard that, for whatever reason (too much shade, etc.), does not grow grass and would be a nice place for a model train.  I looked at G train sets and nearly had a heart attack when I saw the prices (a G locomotive alone costs the same as a full HO set  ).  I have several HO sets that I can put together to make my outdoor garden train, if it is possible. 

Obviously, it would be a bad thing, however (and She Who Must Be Obeyed would be most.....unhappy) if an electrical short burns down the house as a result of my constructing a model train that is not suitable for outdoor use in our yard.

Does anyone have the real answer on this?  I have searched the boards here and have not seen anything definitive, and was hoping I could move forward with my HO plans.  Is it possible to use Bachmann HO trains and track (or any manufacturer's train and/or track, for that matter) outdoors?  Do I need to take any extra precautions to prevent issues that I mentioned above (shorting out, etc.).  Is it basically the same as setting up a G train set, or are there other things I need to take into consideration?

Thanks for your help.