Everything else is enough to play crysis.
Just get a good card and you can play at 1280X1024.
Get either a 9600GT or HD 4670
for this PC Config -
Processor - Pentium Dual core 2.8Ghz
Motherboard - Intel 102Ggc2
Onboard Graphics - ATI radeon Xpress 200 - 256MB
RAM - DDR2 1.5GB ( 1GB + 512MB )
PSU - 450W
DDR2 1GB Card will be enough for enjoying these games in 1024 x 768 or 800 x 600 resolution in 17" CRT ??
If yes , please suggest some DDR2 cards ......