This is what the About Photoshop window looks like on a Macintosh, although it will look similar on a PC. We can see from this window that this is version 3.0 of Adobe Photoshop for the PowerPC, and that it is licensed to ITD at the University of Michigan. Note that this is just a visual example -- Photoshop is a supported product only through Adobe and not through 4-HELP.
Some programs have more extensive "About" windows, and some have less-informative ones. Most of them should tell you what version of their software you are running.