Dunno if its worth the money pouring into a dead memory spec.Max out the ram (512) about $300
NopeWould this info change anything?

AGP4x isnt as big of a handicap as the PCIe marketers would like you to thinkUnfortunately your AGP slot is only 4X, so I dunno if you'll be able to play HL2 and CS with anything out there

Agreed, scrap out whatever is salvageable and try slotting in an AthlonXP/Semperon system.For $500 you might be able to make a better new computer then trying to spend $500 to inprove your old one.
HL2 is more GPU bound than CPU bound although i think balance might be good (9600Pro+CPU upgrade etc)getting that graphic card without upgrading his CPU not going to do much good in playing half life 2