I've used windowsblinds in the past and it was pretty good. If you want the OS X feel then you might want to google Flyakite OSX, although I've installed it on a past windows computer it didn't 'feel' Mac-like.
My routine is to first use XPize to patch uxtheme.dll, change the ugly windows 95 icons that still exist in places for some reason, and change the logins. Then http://www.getskinned.org/ or various forums such as Neowin.net