not sure about US-122-L, but I'm running Win 7 with a US-122
The device driver version is 3.4.0.3, published 8/29/2007, and IIRC, I downloaded it from the Tascam/TEAC website. Another thing that was tricky (again IIRC) was that I had to install the driver in "compatibility mode".
EDIT: I set up my computer to run this way nearly 4 years ago, so the details are a little fuzzy...hope it helps...but I would certainly try looking for the "official" drivers at the Tascam/TEAC, and since the software and hardware are so "old", be sure to run it in compatibility mode.