i got a 7800GS OC'd which is about on par with X1950pro.. so you should be able to play crysis on medium with x4 AA, x8 AS, @ 1280x1024 rez.
what motherboard you got.. ASUS? it could have overclock options in your bios. Ai NOS or even Ai Booster or manual OC settings. it aint gonna cost you anything and its worth a try.
other than that... looks ok X1950pro and 2gb ram.. see if your mobo overclocks too.
you wont have the best comp and it wont last for long but you should get a good few months of gaming out that pc. Then if your serious about gaming, think about building a new pc for DX10 vista.