online store oem softwareWhere is a cheap place and no online stores to get windows or even oem software cheap?

I wanna do a computer build and i am all done but i cant find a good os and i hate linux and i was looking at solaris but i did not know how that would work and if ionline store oem softwarets free but any one know where i can get windows for like under 150 for a installation price not upgrade thanks
I buy all my software at Enu Computers. The link to theironline store oem software site is below, but I'm not sure if they ship - I always go into the store.

They have XP Complete for $100.