You may want to tell us what kind of card they are. If USB, chances are you'll be able to use them with any recent computer & OS. If PCI(e), obviously you may not have such luck.
One point to consider though is bit width. If the card is USB, but oldish, and originally supported 24-bit with a specific driver, chances are that it will only work at 16-bit on a newer OS with the standard UAC drivers. Just something to know. That was a very common "issue" until UAC2, and relatively few cards until recently (just a few years) actually supported UAC2, reason being that it took ages for Windows to get native UAC2 support.
You can use them to record audio... obviously. And analyze audio, there are certainly software tools for this, as suggested above. You could also write your own with your favorite language, whether Python, Julia, Matlab or myriads of others, there are importers for .WAV files and tons of functions that would get you there rather quickly.
If you design audio circuits, that's a pretty decent way of characterizing them. The sound card will act both as a generator and analyzer.
As far as making a low bandwidth oscilloscope out of one, that's a different story. Keep in mind sound cards are AC-coupled. And amplitude-wise, they are not made to be neither accurate nor calibrated (as far as absolute amplitude goes).