hi.you can do a right click on setup.exe and then click on properties and after that in Tab ,compatibility put tick on" compatibility mod" and "Run this program as administrator",after this you can use Proteus in Windows 7 .Another way is using "virtual machine",this software make a virtual Windows XP on your Windows 7 and after that you can install your Proteus on it.you can do this for every software which you cant install in Windows 7.
Regards
pesarirouni