Where do you see the 4pin molex? I haven't seen those on a PCIe card since the days of the 6800/x8xxs.
The P4 will hold you back. GTA4 will be quite bad, the other games you listed slightly less so. You really need to get a new system. I'm not sure I'd pair anything faster then a 9800GT with a P4.
i was talking about the cable spilter that the card comes with it the card itself has a 6 pin connector 2 4 pin molex connector cable is seperate. and will the games be playable with the 4770 currently with the x600se i get roughly 20 fps in crysis and 25 fps in farcry which is good for a 4 year old card.