I have a Fast Track Pro and it's great. It's like yours but with more features.

Guitar Rig isn't an interface it's software :/ Amp modelling software is what you use to mold your guitar into whatever tone you want that it can dish out. If all you're doing is listening to a dry signal of your guitar input, of course it will sound like shit.

You need amp simulators if you're going to use your computer as an amplifier.