HIS is a pretty good brand, but the 5830 isn't the best card to get, since it hugs the 5770 in performance, but the 5850 in cost.
If you'll never ever play anything more than Starcraft 2, then go for a 5770. If you wnat the ability to play something beefier than Starcraft 2 in future without having to go to Crossfire, then go for a 5850.
What're the timings on the RAM?
Cooler Master V8 isn't that good compared to some other cooler out there for a similar price. I don't actually know what they are so other guys can recommend something there.
Rest of the build looks good, but you could swap that case for something with better fundtionality and airflow if you want to. Antec 300 Illusion is great if you want to consider an alternative to the K7B.
You should get some RAM with better timings. The PI kit you listed is good if you're willing to pay the extra.
ah... just re-read your first post and you said mild o'c. With that the Cooler Master Hyper 212+ is pretty good, but it's way too expensive on newegg, so if you can find it somewhere else for around $30 then go for it. Aamazon sells it at a decent price. There are also some good Zalmans at a similar price that're good if you can't find the Hyper at a good price. (don't pay more than $35 for the Hyper)