Hi,
My pc-audio rig is based on parts from the last century.  My comp is a '99 Compaq Presario 5000T with integrated audio, an 800MHz P3 and 512MB RAM.  The headphone minijack is patched to the MiniDisc In (RCAs) on my Aiwa CX-NMT720 5.1 Mini-System (the sub is an Infinity BU-1.)  Go easy on me, I bought these pieces when I was in high school.
My .mp3 collection is mostly 192kbps/44.1kHz becuase over the years i tested formats based on the aiwa's performance and found 160 kbps to be the first bitrate that sounded worse.  Only now (450 albums later) have I learned that I am missing out.  I would like to rip future albums in a lossless format but I am nervous about compatibility issues in the future.  I use Winamp with a .mp3 splicing plug-in.  I have tried DFX but found it made my music harsh(bright?).  Oh, I mostly listen to classic rock, hip-hop, and some of the more instrumental hardcore.
All that being said, I'm trying to figure out the next best step keeping the 80/20 rule in mind.  My goal for my system is to take the computer out of the D/A conversion and just use it as a source.  For this I'd need a digital out or a wire/less network.  Unfortunately, I don't have a digital input on my reciever.  This narrows my options down to a usb audio card, or a squeezebox2 type device.  I haven't found any threads comparing these two devices side by side. I like the wireless aspect of the squeezebox (if it had 802.11g), how does the burr-brown DAC hold up to quasi-audiophile scrutiny?  
I'll stop rambling now, thanks in advance for your help.
-Rick