I did a bit of research on the 122 when I was looking for a soundcard. It sounds ok, usb connect I think. I opted for the Presonus Firebox myself. I'm going to use it with GTP3. I think what you suggested/ are looking into is ok
The 122 is fine. Cubasis, however, sucks balls. The version bundled with the Tascam only has 8-tracks and is 16-bit. It is extremely limiting. For a while, they were offering a free upgrade to Cubase LE, though I'm not sure that they still are. Worth looking into.