Shopping for Windows 7? Score it free or heavily discounted
Student - Microsoft is selling the student edition for $29.99 but you have to be enrolled in a college or university as they require a vailid college or university email. If you don't have one of those, you can scan in your student ID, proof of course payment (yes, I'm serious) or class list. Sheesh.
Home Premium Upgrade - $119.99. You need to be running a genuine copy of Windows XP or Vista to be eligible for this edition. (Sorry to say Microsoft had this on sale for $49.99 up until July 11th when it was sold as a pre order for Win7). Another option would be to buy the Family 3 pack for $149.99, however, Costco is currently selling this version for $134.99.
OEM is an option
OEM licenses specifically ban users from transferring from one PC to another and come with no support from Microsoft, as well as minimal instructions and no packaging. Just the disks. These versions are for small scale computer builders but there's no reason you couldn't buy this and put on your PC with the above mentioned caveats. Additionally, OEM requires a clean install and cannot upgrade previous versions of Windows.
Home Premium OEM 32/64 bit full version- $109.99 (3 pack for $309.99) at Newegg.com. (Free shipping)
Professional OEM 32/64 - $149.99
Ultimate OEM 32/64 - $189.99
Free - check out some other ways to score a free license. Additionally, if you bought a copy of Windows Vista or a qualifying PC running Vista after June 26, 2009, you may be eligible for a free upgrade offer.
Official hoopla page - Microsoft is promoting Windows 7 with a special 7 days of savings on PC's, starting today. Maybe there's something here that will strike your fancy.
Bonus: Thanks to the hot tip from Home Server Show, there's some free anti-virus software downloads that are compatible with Windows 7, including Panda Security,