Question About Vista Accepting Older Games

I am not a gamer, but have Flight Sim FS-9 and strategy games like Riven, Msyt, and Exile and Uru-Ages Beyond Myst. I am sure that FS-9 might play well in Vista, but am concerned about forward compatibility of the other games.

From what I have read and heard about Vista, I am simply not interested in it, and want to retain XP as long as possible. I suppose I will have to accept if I have to buy a new computer, not sure if I can install XP on another computer if I only have the one computer. Not sure if I even have the XP disc, I will have to check. Bought the 8400 a couple of years ago and have been happy with it. Thanks for any ideas.