I would definately pay for downloaded music - but only sometime in the future. I have payed at eMusic before.
For one, a CD quality downlaod takes up quite a bit of space. If I transfereed my 400+ CD's in their entirety to my computer at the 320 bit rate, it would take way too much HD space. You can now get 100GB hard drive, but for pure music downloading, you need much more. If these restrictions weren't there, I would exclusively download. That way (as I already do) I could burn great mix CD's - which I always foind to be better than albums (for the most part).
Also, I have found many hard-to-find singles on the net [ie: Hocus Pocus - Focus]. The CD was out of print, so I was lucky to find it. Granted, I used Napster to my advantage in the past, and didn't buy every CD from every artist I downloaded. But if the equipment is there, I'd be all for it.