So, after some thinking, I've settled my choices, the only real difference between them is the CPU, and ofc, if I get the i3, I can buy the HD 5850 as I have a lot more watts to spare, and the HD 5850 is better than the HD 6850, and from benchmarks I've seen, the i3 2100 performs the same as or better than the Athlon 640 with less than 30W of the Athlon's power usage.
Btw, I can't change these parts, they come prebuilt, so please don't suggest it.
The Intel® Core™ I3 2100 really is a nice processor for the price. Overall I would say that the Intel® Core™ I3 2100 build should get you started into the 2nd generation Intel® Core™ processor family and will make it very easy for you to upgrade in the future if you so choice.
Looking at more Benchmarks, the i3 2100 performs the same as/better than the PII 970, I think I might grab a i3 2120, as it is an upgrade choice, but thats the most. Btw, what about games that like Quad cores, BFBC2 for example, would I be able to run this as good with HT on this Dual Core.