including crysis:
2gb ram,c2d or c2q atleast more tan 2.4Ghz,for hi settings:8800GT or higher..mid:8600gt or higher,low settings 7600gt or higher...for very high..nvidia 9800GX2,ati HD3870x2,8800 ultra,9800GTX or 8800GTX although the 2 GTX cards may still be laggy under very hi...i have no probs wid my card at Vhi always above 25fps usually above 35 depends on ur resolution...
without crysis:
1-2GB RAM,c2d cpu is suggested,8600GT or higher but id rather go for a 9600GT or 8800GT rather tan the 860gt...