METHOD 1(this is how I did it)
1.You will need a torrent downloading program
I suggest utorrent.
2. Go to the following website and download the torrent.
Windows 7 Download
3. Download a program called magiciso.
4. From that program burn the "image" you downloaded from utorrent onto a DVD.
5. MAKE SURE YOU BACK UP ALL YOUR FILES. I WILL NOT BE HELD RESPONSIBLE FOR WHAT YOU LOSE!
6. Insert the DVD you burned and follow the steps.
Download the file from there(you need to register and do a bunch of other junk) and then after you download the file you basically just follow the steps I showed you earlier, but they have clear instructions on the site on how to go about installing the new Windows 7.
Write in the shoutbox also =D