CPU: i5 2400 $180
Mobo: ASRock Z68 Pro3 Gen3 $110
Case: Something budgety around $60
VGA: HD6770 $110
PSU: 500-600W ThermalTake Litepower or CoolerMaster Extreme or similar $80
CPU HSF: Xigmatek Gaia or CM Hyper 212+ $30
HDD: Seagate 500GB $75
Optical Drive: Liteon $20
RAM: G.Skill 1600 8G: $50
If you like AMD, go with the x6 1100T for about $170 if its still available, if not, then FX-6100 $170. Motherboard should still be around the same price. ASRock motherboards are easier to overclock, and are generally the best value for budget builds.
Oh well for a summer build Phenoms will not be available, but by then Ivy Bridge and Piledriver will probably be out, which changes things a lot. Also HDD prices would have halved. So I think its a bit early to decide now.
The new Intel line of processors will be out by summer, as well as AMD's and Nvidia's new graphic cards. With a little luck, HDDs prices will also go down as azeng mentioned.
What this means for you is that the build we suggest for you now will be completely different by the time we get to summer. So, for now, just hang tight, sit on your money or maybe even save up a bit more for your system. When summer roles around, come back to the forum and we'll be more than happy to suggest a build for you : )