I have EQ5 running on Windows 7 Pro. I 'restored' EQ5 when I purchased this computer. It runs ok but there are some graphic and saving glitches along the way. Everything works but just not as easy as it was when I was running 5 on my old Windows 3 computer. I agree with cashs_mom to check your computer and both versions to see which is compatible with your machine. That would be the compelling factor for me if I were in your shoes.
EQ5 does everything I need it to do for my purposes but I don't use it that often nor do I do that much 'designing' vs 'changing' a given pattern. Depends on your needs/desires.