Newbie re Wireless Transfer

I don't have a sophisticated system and very little experience in PC audio. I have read hundreds of posts but it is hard to understand if you are not familar with the products and terminology.

I am using Windows XP via usb to a Fubar ll DAC in to Audioengine A5 powered speakers. I listen to downloaded music occasionally but mostly streaming radio via WinAmp.

I am on a budget here and wondering

1. How I can improve the sound with software? I understand K-Mixer is to be avoided but I don't know if Foobar or any of the other players pass streaming audio.

2. Can I send audio from my computer to my main stereo in other room not only wireless, but on the cheap? I think Audioengine sells a set of dongles to do this but my main stereo doesn't have a USB input.
The best and probably the cheapest way to do what you want is to use Apple iTunes on Windows XP and buy an Apple Airport Express with Air Tunes for the other room. iTunes can stream audio files from your PC to Airport Express via wireless. Airport Express has a built-in DAC. You can get audio out of it into your secondary system.
I'll check that out. Thanks much.