I just acquired this program a couple of days ago and have it running as an RTAS plugin in my Pro Tools LE/Mbox setup on my PC.
I've tried PodXT, VOX Tonelab and even the VOX ad30 amp (i take full advantage of Guitar Centers return policy). None of them really cut it in my opinion.
The Guitar Rig is an amp/effect modeling program.
All the amps and rack effects are "drag and drop." super easy to use and it sounds really good. lately ive been a tube amp snob. I would rather play through a tiny fender blues jr than a large solid state amp any day.
The Guitar Rig really does a good job of getting that warm tube sound. I plug my guitar through a nice tube preamp and that may have something to do with it too but if you can get this program youll have a lot of fun with it.