Do the other PCs show 44 or 48? 44 KHz is non-standard, 44.1 KHz is standard. If you are seeing 48 KHz then the audio is being changed fro 44.1KHz (CD standard) to 48KHz. Many PC systems convert to 48KHz which will downgrade the sound.
This gets a little technical, but hopefully it will make sense.
You should look at what audio format is being used for the usb output. My guess is that may be causing the differences you here. In general XP was not a good sounding OS, whereas Windows 7 was a big improvement. Windows 7 introduced WASAPI, which bypasses the Windows audio system. Direct Sound, the old system, uses the Windows audio system, which can degrade the sound. It would also explain why you have 48 KHz. Do not believe WASAPI was available on XP.
J River is a very good player, although it can be a little complicated to get used to. It is $50 and then updates are about $20 after that. It has a free 30 day trial. Foolbar is free, but the user interface is generally not as good and tends to be somewhat technical.
flac is the most common format to replace wav on windows. It is a compressed version of wav, although there is no loss of data) and it has better tagging capabilities. A program like JRiver can convert to flac and rip to flac.
I would get a Windows 7 system with WASAPI going using something like JRiver or foobar and see how that sounds. If you need help getting J RIver set up, ask for help.
This gets a little technical, but hopefully it will make sense.
You should look at what audio format is being used for the usb output. My guess is that may be causing the differences you here. In general XP was not a good sounding OS, whereas Windows 7 was a big improvement. Windows 7 introduced WASAPI, which bypasses the Windows audio system. Direct Sound, the old system, uses the Windows audio system, which can degrade the sound. It would also explain why you have 48 KHz. Do not believe WASAPI was available on XP.
J River is a very good player, although it can be a little complicated to get used to. It is $50 and then updates are about $20 after that. It has a free 30 day trial. Foolbar is free, but the user interface is generally not as good and tends to be somewhat technical.
flac is the most common format to replace wav on windows. It is a compressed version of wav, although there is no loss of data) and it has better tagging capabilities. A program like JRiver can convert to flac and rip to flac.
I would get a Windows 7 system with WASAPI going using something like JRiver or foobar and see how that sounds. If you need help getting J RIver set up, ask for help.