How to Get Windows 7/8 Cheap

I am going to build my new $700 gaming rg in month or two but I am having money issues because I am only 14. Most things I need such as Monitors or Keyboards I can find cheap on Ebay. But if you have any suggestions to how or where to get a Legal copy of Windows or any other accessories such as Monitors for a cheap price then retail.

Also I wish to know more about Linux. What exactly is it? I got into it because it was free.... i think.

You can try these (now i have no idea if there repitable as i cant order from them as i an in the uk but i have given the link out many times here and no one has sead that thay havent goten a copy but it's at you'r own risk) i'ts a standard oem copy thats just DEL branded

i was going to buy windows from missionsofts, then when i read lots of complaints and a failure on the bbb's site... make of that what you will, but i went with this instead (it does require a bit more to get at first, but i'm trusting the rebate)

Buy an OEM version from somewhere like newegg. Just make sure you buy a part for the machine at the same time.