I'm not a wiring expert, but I have made many a patch cable in my day and was a .com kid before "retiring" to the trades
I just want to clarify one thing. Cat3 is NOT rated for 100Mb. (Mb = megabit... MB = megabyte.. M = ??) It may be possible to use fewer pairs, but you really should run Cat5 for network connections, though with wireless as cheap as it is, there's very little to waste the cost on the wire/labor to install. Only makes sense if you are running the CATV and such too.
Also if you're going to pull for phones & network just pull Cat5 for both. And really use Cat5e if you're going to go through the bother. Use the combo jacks for either RJ-11's or RJ-45's and a small patch panel in the basement or wherever and you can switch outlets between phones/data. I did this in my house in 2001 and within 1 year of doing it my phones are all wireless and so are my computers, so... kind of unnecessary!
Yeah I know that technically there are only two pairs used (green and orange if I'm not mistaken), but I believe the others are necessary to keep high signal/noise ratio. If you are splitting Cat5 into two carriers, you are likely having problems that you might not know about. I'm curious as to your packet loss stats?
Anyway, your audio/video sounds cool.. Do you just have a component closet away from the main tv or are you distributing HD signlas through the house? Using a Media-center pc? A seriously funky integrated amp? The only other thing I could figure is a thermostat wire for remote control or IR repeater if you want remote rooms to be able to control... unless of course it's pc-based and you could just use the network!
Oh, and speaker wire... The one thing probably not wireless.. for now..
- Jared