"I dont think I have ever seen a hardware modem that is an ISA???
--- Go with a 3Com"
Most ISA modems are hardware, but there are some crappy ISA winmodems. The new PCI winmodems usually work great and sometimes outperform hardware modems, though. IT REALLY DEPENDS ON YOUR SITUATION! Generally hardware modems perform better under worse circumstances. For example, you could get 49333 with a hardware modem on crappy lines, and only 21600 with a winmodem. If you have a good phone line though, it may not matter, you may even get better performance with the winmodem.
Personally, to be safe, I stick with hardware modems. The best brand to go with would probably be U.S. Robotics (NOT 3COM, they are seperate again). I have a 33.6 USR modem and it works great, it performs as well as many 56k of today. I have a newer "half/half" 56k 3com. It works well, but a little slower than the completely hardware ISA 56K 3com I USED to have. Just to put things into perspective for ya.
If you want to save a buck, buy a GVC modem. Very fast and stable, and probably half the price of a USR.