HELP with MOBO AND CPU please

As the title says, can you guys give me recommendation for a mobo and cpu? What I have in mind so far is the e8400 but I have no idea about what mobo to pair it up to? I have all other components for my comp. I will be using this comp mostly for surfing, music, and occasional gaming. I want to be able to play the upcoming Starcraft II with no problems. That's the only game I will be playing and occasionally CS 1.6. I don't want to spend too much so what's the best, budget or bang for buck mobo and cpu I can get that is reliable ? I'll be using 4 gigs of RAM and will be using windows xp or vista ultimate.

Your input is very much appreciated! Thanks for your time!

Budget is $500. I don't know how many watts my PSU is because my friend is the one who built it for me and I never bothered to ask. GPU, I'm going to go with a 8800 GT. CPU, I'm probably going to get an e8400. Suggestions for a good, reliable mobo?