As long as you understand ISA vs. PCI vs. PCI-e, than another question is: Is my sound card supported in my OS.
For example, I had a Sound Blaster Live! PCI sound card, which is unsupported in Windows 7. No drivers, no sound, lots of problems, not resolvable!
Also, the onboard sound on my old Asus P4-800 Deluxe mobo was unsupported!
Check the Window Compatibility website.