We've had customers with this request for Server 2003 machines with a sound card. They were using RDP to listen to music before they pushed it to their radio stream. I would say the only thing that may be an issue with your request is the Windows XP part.
And 1TB of bandwidth is nothing, its minimally the industry standard for dedicated servers.
On a serious note, your best bet is to ask hosts that your interested in if that is something they can equip your server with. Maybe a host will just charge you for the card and installation, if it gets them a new customer they have nothing to lose.
1 terrabyte is nothing. I don't think any host states a sound card option but i'm willing to bet any host will install one if you mail one to them + pay for their time. Another option is colocation, of course.