How truly inferior is it to the AMD Athlon 6000+? If I overclock the 5400 to 3 ghz, will it get the same performance as a 6000+?

I ask this because my dad's 6000+ 2gb of ram 7800 GT runs Crysis all medium on fine. I am thinking of getting a 5400+ to compliment my 2 gig of ram and 8800 GT.

PS: When I stick my 8800 GT intohis computer, it runs all on very high (dx9 hack) at nearly 40 FPS. Constantly.

Is it really worh spending $160 for the 6000+ instead of $99 for the 5400+?