Second, I think for PC soundmakers in particular, drivers are often at least as important as features on the card. Understanding what kind of drivers are out there, and what they can do for you, is critical to making the right choice in audio hardware and software. The biggest downside of making music on a computer is that computers break, and when the computer breaks, you have to stop playing and writing and programming and fix the damn thing. If you're lucky, you still remember what you were working on and aren't so frustrated that it's painful to play. Often, you're not so lucky, and that tune or idea or beat is gone.
Nothing insures lack of productivity with audio software more than buggy and unreliable drivers.
It's also one of the toughest things to figure out when you are buying a card, because of the potential variables involved. Every computer will have different quirks-the CPU, the supporting chipset, the video card, and so on. This leaves you, the consumer, best served by gathering LOTS of information before you make a choice of what software to use with what card. This, by the way, is one of the advantages of some of the more expensive systems that include hardware locked to certain software. It sort of blocks out the entire issue of drivers, because the software only works with one piece of hardware, and it can be hand tweaked to perform properly.