That PC should have enough space for a dual-boot install of both Windows 7 and Windows XP. However, I will not recommend it. Yes, it works for me, but it is a hassle to do.
Instead, may I suggest you try different browsers. Besides IE, Firefox and Chrome, your could also try:
Opera
Lunascape 6
Sea-MonkeyAnd there are lots of others.
I think your problem is the browser, not the Operating System (OS).
My preference is Firefox. I like version 33.1
http://filehippo.com/download_firefox/59294/But if not, use Windows 7 to free up some space on the hard drive (shrink) and create a new primary partition for Windows XP. After you install XP, the Windows 7 will not boot uyntill you do a repair from a Windows 7 recovery disc. Which you would prepare ahead of time.