I want to know what the main weak spot is on my system. Here are my specs.

Athlon 1.2ghz T-Bird (133FSB)
512mb CAS 3 PC133
Geforce 3 Ti200

I plan on upgrading my whole system soon, but I'm curious as to what's the main bottlneck when playings games (especially Far Cry, the first game that REALLY brought my computer to its knees).