The games mentioned are all different, i would think CoD 4, FIFA, NFS will be no problem at all.
Farcry 2 needs some patching so you will be able to run it but i understand tere are problems with the game. Crysis will run but not at top spec, you would need to upgrade to a HD4870.
Its worth noting that your 4gb ram and Quad core proc is not being fully utilised without a 64bit OS like Vista Ultimate
How many years will this system run new games at high settings? Thats a hard question to answer, but i would say in 12 months you should reassess the market for upgrades. This setup is fine for most things out there at the mo (Crysis being the current pinnacle)