Well, I don't know. I've got my home network running on Cat2/3 (that's what was here when I started replacing my asynchronous pc-pc connections with a LAN), and while accessing the 3MB DSL on a 5MB LAN is fine, I think I'd rather transfer files and back stuff up on a 100mbs connection.
There's a place for everything. Cat 3 for Voice and Cat 5E/6 for Data.
Personally, I can't wait for CAT 7. We're going to "have to" replace all the data cabling for these Yahoos who HAVE TO have the latest and the greatest.
Sam