New
#21
You can "only" download and install Windows XP Mode if you own Windows 7 Professional, Windows 7 Enterprise or Windows 7 Ultimate. You said previously that your computer had Windows 7 Home Premium, and that doesn't entitle you to use XP Mode. If you have one of the required OS's, when you install Windows XP Mode it simply will NOT prompt you for a key.
My apologies, I screwed up. The version I meant was 3.1.5...not 3.5 at all.