Hi - I'm the guy who wrote that article. I hadn't tried converting any images recently (once I moved off Virtual PC, I never looked back), but I tried again tonight to see if anything had changed. It turns out that not much has changed at all.
I grabbed a virtual disk that Microsoft published to test IE6, tried to concoct a VPC to go with it, and ended up using VMWare's converter to convert this virtual disk to a VMWare disk. It opened just fine in VMWare Server, and when I powered up, the machine discovered some new hardware devices and asked for the drivers from the XP disk, just as I'd seen before. This, I believe, is due to the emulation differences between Virtual PC and VMWare.
I haven't gone and tracked down the drivers this VM is looking for, because I don't plan to keep it around for long, but my recollection is that once these are set up, the VM will work just fine.