Ditto on the DO NOT GET THE 460 SE... that thing won't let you play max settings... A single GTX 460 1GB is a really good price if you shop around and offers way better performance than the SE version.
Yep, if you plan to o/c both the CPU and GPU, I'd get at least 600w, maybe 650w to be safe. I can't really comment on Biostar mobos, but I am always hesitant about the 'cheap' brand. I've heard some people give biostar good raves, and other say it's cheap ****.
Yep, if you do a little shopping around, you can definitely get a better PSU for a good price. Does
NCIXUS.com - Great Technology, Selection and Service. not do price matching?