The trick is getting your card set up first. I'm using one of those and had all kinds of weird problems getting it going. Make sure you have the most current drivers, or even a version or two back I have heard is preferrable. It depends on what type of system you are running, but assuming you use an external mixer for your input device, and some type of monitors, I have had the best luck with setting up the monitor mixer to choose my input as H/W in 1/2 and the output as H/W in 1/2. Make sure your volumes are up all the way and selected (not muted). Make sure you go into your PC control panel into sounds, preferences, and choose the M-Audio card as your preferred play back AND recording device. At this point you should be getting play back and recordablity. In cool edit you'll need to go into options - preferences - and set your default record and playback devices to M Audio H/W in 1/2 (both playback and record). I've used the M-Audio delta monitor mixer selection as well, but got better performance with the H/W in 1/2.
The problem I had when I first installed the card was it was acting like it wasn't a full duplex sound card; I couldn't play back and record at the same time, only one or the other. If you run across that- it's not true! You just have something not selected right.