[baccilus]

Upgrading the proccy later is a super excellent idea. Buy a mobo that will support intels upcoming penryn processor.
If you play on XP, you will do fine even with that proccy. I have a P4, 2.66GHz processor, 1G RAM and an 8500GT and even I can play crysis pretty well( on low settings though, but it is still fun). And you will play other games with good settings. I play COD4 in strictly medium settings without a lag.

If nothing else, ( later) you will at least get a better C2D. for the same money. And I think you will also manage more money by then.
Your processor is not too lame at the moment. Believe me( mine is !)