The recent SBM pc's of this website have shown that the E7x00 series isn't really worth purchasing since it...
1. Doesn't overclock as well as the E5x00
2. Doesn't get much extra performance from the extra 1MB of cache.
I must agree with shortstuff_mt on the E8400 potential upgrade.
However, I would purchase the E8400 + HD4850 over the E5200 + HD4870. Video cards are much easier to replace in the future. (And, we all know that video cards are generally replaced every 2-3 years in gaming pc.s.)