the computer can do this and much more if you have a decent machine. when you stream your music, how much cpu are you using? are you telling me that you are maxing out your cpu? the computer has to do quite a bit of work to get data off the disk, into it's memory buffers, and then package it up to send it over the network. all of this messaging of data happens in memory, after it is read from disk. if you system is using less than 80% of your cpu, it is not a big deal. now if you are saturating the cpu, now you need to offload some processing.
I don't believe streaming music, either from the native hard drive, nor from an optical drive, is very CPU nor memory intensive. My tower is a dual 2.7ghz processor. I can monitor CPU usage in real time on the Activity Monitor utility. Streaming files from itunes runs average around 4-6% capacity of the CPU with a few spikes now and then to 13% which are very brief. It take 87mb of real memory and around 1gb of virtual memory to stream music as well. Not even close to the machines capacities on any of those demands. I have three Squeezebox devices around the house and can stream music to all three, different tunes to each one, without a hiccup and still check email and surf the Internet. This is on a Mac. The Squeezebox interface does use the iTunes library, but NOT iTunes. It uses a web browser and indicates even less usage of the computers resources than iTunes demands. It is not a demanding task for a computer as far as I can tell. I'm comparing it to something like Photoshop, video or gaming software that is very graphics intensive. Someone correct me if I'm wrong.