USB audio got a bad rap from the early days when they weren't so good. They're very good now and audiophiles are using USB DACs and USB audio interfaces now.
I find USB devices easier to connect than PCI cards. With PCI you have to open the computer case and have to reach around back of the computer to plug in cables. USB devices can also be used with laptops. But PCI cards can be less expensive than USB DACs. It's a tradeoff.
The pro audio (home studio) oriented cards like the EMU and M-Audio and others are also options. I didn't mention them because they're more complicated to set up. They have more inputs and outputs. Some inputs and outputs may be balanced while others are unbalanced. You may need adapters to convert an output to unbalanced RCA. If you're comfortable getting a little "geek" and understanding the different pro audio style inputs and outputs you can do well with a pro audio style audio device. Prices for the pro style gear can be competitive and well in your budget.
The EMU 0404 USB and 0202 USB are fairly straight-forward to set up. They have a regular line level unbalanced 1/8" output jack on the back. Plug in a 1/8" to RCA 'Y' cable and you'll be ready to go. You can also use two
1/4" mono to RCA adapters with the EMU and most other pro audio style cards/devices to connect regular RCA audio cables.
My computer based audio setup uses an M-Audio FireWire audio interface. It's a home studio pro audio style device. It works well, just a little bit more complicated to set up.