Hello all, this is my first question on this forum

I was just wondering what would be the best thing to upgrade on my pc to increase my game performance

Here are my specs:

Processor: AMD Athlon 64 X2 5600+ (2.8 ghz)
RAM: 2GB running at DDR2-666
Graphics Card: Sapphire HD3870

I just want to be able to run crysis at fairly high quality, with a fairly high framerate

Thanks for any response, Leander24.