Yea, definitely. I think USB is a future-proof way to go seeing that there's less and less PCI slots on motherboards (some don't even have any). It really depends on the computer though. Grounding issues can introduce noise, so can certain hardware devices. There's just endless combinations that can cause problems. However, someone thought ahead and fixed that. There's devices like this:
http://electronicsshop.dk/isoleret_usb.htmAlthough, I don't remember it being $48... Might wanna look around. They do exist and they're pretty common so it shouldn't be too hard to find one. I think it also depends on the sound card too though. Like on my D1 DAC, I can hear my mouse but on the same USB port, it's silent using my Teralink X2 USB to SPDIF converter.
I would say go for a USB device and if you have issues, look for one of those isolation devices.