Here are the problems:
You need to rectify the 8-pin requirement. I'm not very comfortable with the 6-pin adapter theory. If it needs an 8-pin connector, give it 8-pins! No point risking your card getting fried.
1 gig of RAM isn't enough for Crysis. Get yourself 2 gigs on DDR3 instead of DDR2
Too low buddy....consider upgrading that, at least to a Core2Quad@2.4
Probably not what you wanted to hear, but its the truth.