I've been running a PC front end for over a year now, and I second the comments regarding Jplay, I wouldn't use a computer based front end without it. It is a must have on a PC based system, made a *huge* improvement in sound quality on my rig, one that was immediately apparent. Jplay can run in Jriver and Foobar, can also play with iTunes but the two don't play as well together.
Also consider using a USB converter and buying a less expensive DAC, but one that still accepts high res input. In my experience this route usually yields better SQ than buying a USB DAC. The best shootout of USB converters I have read on the 'net can be found here:
http://www.computeraudiophile.com/f6-dac-digital-analog-conversion/15-usb-spdif-converters-shootout-15327/
Also consider using a USB converter and buying a less expensive DAC, but one that still accepts high res input. In my experience this route usually yields better SQ than buying a USB DAC. The best shootout of USB converters I have read on the 'net can be found here:
http://www.computeraudiophile.com/f6-dac-digital-analog-conversion/15-usb-spdif-converters-shootout-15327/