well for now days its useless to have the total system i think...
as with Dual Core and Vista on market, application will go more resource hungry every day....
U better think of a New system... as keeping it would increase our maintanace cost, some what... and when thinking of new procy or any thing, nothing would match with ur present system...
Its wise to go for a complete upgreade... if not now then, keep using this system, start saving money, and then go for one new system based on C2D and G965 and Dual Channel DDR-II and SATA-2 and etc, etc