Yeah the one place you really want to spend the extra money for a PC is in the PSU. better safe then sorry imo.
+1, couldn't agree more.
tbh, id recomend you spring for a corsair PSU instead of coolermaster. ive had a bad expereince recently with a CM PSU needing to be replaced, when it should have been capable in a system.
seems like a good build though, very good balance of parts.
EDIT: lol, seems this one is actually cheaper: http://www.newegg.com/Product/Product.aspx?Item=N82E16817139004&Tpk=corsair%20550
a better PSU, and probably capable of supplying more watts than the CM one. definitely a better choice.