good pointers. On 64-bit versions there's also a 'Program Files (x86)' alternative. If that also fails to install or run thereafter, you could install under one of the folders that you have total ownership of, something you create in 'My Documents' or equivalent, or a folder on the desktop. That way you know that UAC won't interfere. Still, UAC may interfere with installation of some .dll's or ocx's or other items normally going into the System32 folder or other system area. That you may need UAC disabled for at least temporarily. I don't recommend UAC disabled constantly. UAC has its reasons and they're valid for security against trojans and other malware.

Compatibility mode: excellent point.

There's also nin windows 7 a thing called Desktop Compositions, you may need to disable that too. Try with it, then without it. Look at the other options in this Compatility panel, this one is win7, Vista may not have all these options... See image attached.

If the program was made for and tested with XP sp2, you may want to run it in compatibility mode for XP SP2. The screenshot example shows SP3, which is more restricting in some ways than SP2.

Yes get at least 5.5, free.