There is a utility on the Microsoft website
that will check your system to see if it is Windows Vista compatible. It is a good utility, but requires you to install it on each system you want to check before running it. I recommend you install the application on one computer, then copy the contents of the folder it was installed to to a memory stick to run in multiple locations. It does not require an install to run properly, as long as you have the .NET framework.
I have a zip file available locally to download that can run from a memory stick.
On a side note, since I do not plan on upgrading to Vista myself, I cannot support the use of any of my free software on that operating system. Someday, in the future, possibly after service pack 2 or 3, I may upgrade, but for now, the only operating systems I can truly state that my software works on are Windows 98/ME/2000/XP/2003. Oh, and some of the applications written in VB6 will run under WINE