When I hooked my V-Amp 2 to my PC (WIN XP) via M-Audio 1x1 midi USB, it gave me a little flack at first. I hooked up the interface, and then when it asked for the drivers, I pointed it to the driver CD ROM. It did it's thing, then rebooted. Still no light on the midi interface. Un-plugged it then plugged it back into the USB port. It popped up again that it needed the drivers. Walked through a shorted version of the driver intall process, though it didn't need the CD this time. Then I had finally had a light come on. Plugged in the V-Amp to the midi interface. (USB midi out > v-amp2 midi in, V-AMp2 midi out>USB midi in), and it popped up a driver install AGAIN. Cancelled it and got into the v-amp program and it didn't detect a device. Ok, unplugged v-amp from midi interface, and plugged in again. Popped up the driver install again. This time i clicked through it. Got into the V-AMP 2 program and FINALLY, saw all the patches, etc.
The conclusion I came to, is that each time it was popping up that driver install window, it was for a different device or at least the PC saw each component as a different device. So basically it needed to set up the driver for each part of the chain.
Also, once I got it working it was worth all of the trouble. It kicks ASS! You can change various settings for the effects, and each setting is labeled pretty clearly as to what it changes. Also, you are able to configure just about any combination of effects TOGETHER. Which is something the basic V-Amp2 doesn't let you do, or at least not that I could figure out. You can move patches around, put all the ones you use in the order you use them. Back up your V-AMP settings in case you lose them, and other stuff that I have forgotten to mention.
Hope it works for you!