Well, the 2.8C is $38 cheaper than the 3.0C from Newegg, and you can overclock it to 3.0 easily. For overclocking it's always a crapshoot, but the 2.8 will give you better memory bandwidth at the same clock speed because it will have a higher FSB. It is possible that the 3.0 is slightly more likely to achieve a higher overclock, however.
So basically I am looking at a cost to performance ratio. If Iwant to play Doom 3 once I am able to run it. Either the 2.8 or the 3.0 will give me the performance. Since now most games are taking more advantage of the video card than the CPU.