dude today i talked a technician here , they told 1gb ddr2 stick set (512x2) is only Rs180 from starlite , it is few cents more than a 2dollar.
When you got your pc running , instal usp4 over sp2 to get modern things and being full patch
For av i would like to suggest following avast free + Privacyware firewall with Malware byte antiExploit.