Microsoft have decided to do something about the relative instability of Windows device drivers. They are, by all accounts, very hard to write.
Interesting point: the Kernel-Mode Driver Framework will be supported in Windows 2000 and later (i.e. a lot of it will be compiled into/linked into the driver binary). I also see that USB device drivers will be moving into user-mode for Longhorn.
I recently had to update a CE device's OS image using a special download program and the device's Initial Program Loader, over a USB connection. The device required a special driver - which promptly crashed my PC (with a KMODE_EXCEPTION_NOT_HANDLED fault). I suspect a possible incompatibility with XP SP1 with the MS04-011 patch. Using an unpatched Windows 2000 SP4 box worked. Of course, I couldn't use Virtual PC, because it doesn't virtualise USB controllers, hubs or devices.