I'm sure a few of my comments below are repeated but here goes:
1: Create a virtual machine: Yup and pay for the licensing cost for the old version of Windows [reminder that an OEM license stays with the computer it was bought with - can't go in a VM]. Don't forget maintenance [i.e. AV, security updates].
2: Turn off User Account Control: I think I read someone that turning off UAC also disables something in IE [not critical if not using] but also reduces security in general. Fine for a techie but not a typical user.
3: Install .NET Framework 3.5: A proper installer would check if it's installed.
8: Trick the application....: Or right click on the application, go to Properties and then Compatability tab. Choose the OS it works fine with. In some cases, you may get the UAC window when opening. In some cases, the video resolution or bit level may have to be dropped.
Obviously some options are useful in a mass deployment. Then try the Microsoft Application Compatability Tool Kit.
You can also try application virtualization from Microsoft, VMware or others.
I used Adobe's PageMaker up until last year in Windows 7 64-bit. this was an applications last updated in 2001 - before Windows XP came out and yet it worked fine in every OS that I used it in [except one minor glitch] and obviously not a 64-bit app.