Bought a license 9 years ago...used it for quite a while, and then had various Microsoft Intellitype keyboards and used MS's pref pane instead for customization (I'm no fan of MS, but they make a damn fine, comfortable, usable keyboard)
Then, with Snow Leopard, the IntelliType and IntelliMouse pref pane/driver mostly broke, and the MS site says there won't be a SL compatible pref pane until mid-October. (I posted info and the MS link at a recent review of the Intellitype software here on MacUpdate.)
Since I make a living with my keyboard, I really was in a bind, because I can barely type on a regular keyboard after being so spoiled by the comfortable, splayed-hand layout of the IntelliType boards....so, I thought, "Well, USBOverdrive was always rock solid for me, wonder if it will talk to my IntelliType Natural Ergonomic 4000 keyboard." I downloaded it, tried, and was able to get back 95% of my IntelliType's special keys (the only thing USBOverdrive can't seem to program are the special "My Favorites" keys (1 through 5) although it *can* program the "star* key that the MS pref pane uses to program those 5 keys. Also, USB doesn't see the Windows "Apps" key on the right side of the keyboard, but I never used that even with the MS pref pane.)
So, to save my bacon, I happily bought a new copy of USBOverdrive and consider it money very well-spent. Not only can it program the heck out of just about any keyboard, including MS's Ergonomic Seri9es, but almost any mouse, giving full-functionality to my MS Laser 6000 cordless mouse to boot. (Of course, it also does all kinds of joysticks and other USB devices, but I don't use them.)
If I didn't want to be able to finally program "My Favorites" keys, I probably would just dump the MS pref panes for good -- but when MS finally comes out with the new pref panes, I'll probably want to program my "My Favorites" -- it's so handy to punch a button to open an app, switch, run a script -- almost anything you can think of. In the meantime, I'm very, very happy with USB Overdrive X 3.0 and am making my own "favorites" with various F-key combos. Hmmm, maybe I won't go back after all. :)
Anyway, this is a rock-solid, feature-packed piece of software with a very reasonable price and I highly recommend it to anyone who want to program their keyboard or mouse. It was a real god-send to me in my work.