Orange Box for PC

Alright /games/, I was wondering about the stability of my game.  I have a decent computer config for an older pc (1 gig ram, radeon 9500) but I only have a pentium 4 1.6ghz processor, single core.

I played a pirated version of portal, and it worked fine, but how well will my computer be able to play TF2 or HL2EP2?

It says on the box about the minimum requirements.