I bought a M-Audio Fast Track, same thing I think, with two inputs... Anyway, I was running Win 7 64 bit with 4gbs ram... My recordings had the occasional pop and crackle that comes from latency issues. Needless to say I dont use that thing anymore. I stumbled across something else that works like a champ, my POD X3! It works as a great audio interface when plugged in via USB and hasn't given me one problem with win 7 64. It essentially has 3 inputs, Gtr1, Gtr2(or aux), and a mic (gtr 1&2 could be used for mics as well as long they dont require phantom power and you have the 1/4"plug). Anyway, it does everything Fast Tracks claimed to do, but without the pops and crackles... Just dont use the amp sims or effects if you already like the sound of your rig. You could probably buy a used one for around $350, maybe less.
Im in Afghanistan right now with my extremely "mobile" studio, it consists of my laptop, my pod X3, Shure m58, Schecter Hellraiser, and a pair of sony monitor headphones (which suck balls to mix with). Anyway, the POD X3 works better as an audio interface than it does as a modeler, IMO.