go to tomshardware.com and look for gaming pc parts and that is what you want. if you dont know then just get a Hot Dell or an Ailenware gaming PC there are tons of them that are just killer now from the manufacture. if you want hot for 3 years your going to need to spend at least $2200, upgrade the video card and the monitor to as much as you can afford any Pentium4 like 3Ghz is fine or an AMD 64bit job would be killer.
As far as sims go i love AFP its like $140 now from OMP
its the only sim i know of that 3d's out of the box without heavy tweeking, the ribbon thing is great sequences
and you can do realistic flat spins because the stall phisics is realistic, i know some G2 guys got it working good now so it will work fine if thats what you got.
i do the same thing as rcplanefan, rolling circles for hours, i daydream about them after a while, close to the ground is too fun!