(Cross posted from L/J...)

After much fiddling, it turns out that one can get the Griffin PowerMate to work under Vista. You just need some patience. And a bit of luck.

In particular, you need to:

1. Run the installer.
2. Copy the Control Panel Applet, PowerMate.cpl, from the installation media to C:\Windows\System32\. (If you don't have the original installation media, you can use a universal extractor to grab the files from the installer, or just install the software onto a different machine and find all the files by hand.)
3. Copy the PowerMate.exe file from the installation media to your C:\Program Files\Griffin Technology\PowerMate\ install directory.
4. Copy the PowrMate.sys file from the installation media's System32\Drivers\Windows2KXP\ directory to your C:\Program Files\Griffin Technology\PowerMate\Driver sub-directory.
5. Load up the Device Manager and look for the Human Interface Device with the hardware ID "USB\VID_077D&PId_0410". (If you can't find the device, you may need to unplug it and plug it back in as Vista may tag it as non-functional by default.) Choose to update the driver, and browse your computer for the driver software. Opt to pick from a list of device drivers on my computer, and then click on the "Have Disk" button. Select the C:\Program Files\Griffin Technology\PowerMate\Driver sub-directory with the PowrMate.inf and PowrMate.sys.
6. Run the PowerMate.cpl as an administrator to set all of your powermate settings.  (Just browse to C:\Windows\System32\, select PowerMate.cpl and Run as Administrator.)  This will ensure that the PowerMate executable, which we'll also run as administrator, loads the correct settings.
7. Lastly, you'll need to set the PowerMate executable to run in app-compat mode so that it’ll have access to the hardware volume, rather than getting its own independent application volume.  Also, you'll need to run it as an administrator.  Right click on the PowerMate.exe file and select properties, navigate to the Compatibility tab, and then Show Settings for All Users.  Choose to Run this program in Compatibility mode for Windows XP (SP2) and Run as an administrator.
8. Run PowerMate.exe.

OK, so probably not worth the effort, but there was geek pride at stake here... ;-)

BTW, this was also pretty neat. Clearly the answer the next time is to write code to solve the problem.

Hopefully this will help others running into the same issue.