> and the network is not likely to be
> initially 100Mbs, but since we're putting this wiring in the walls, it
> would be nice (if it were not too extra costly) to wire it for that
> eventuality.

As others have pointed out, Cat 5 cable is very close in cost to Cat 3, so
you might as well go for Cat 5 and be ready for 100Mbps.

However, a couple of years ago, in a USENET discussion on the relative merits
of coax versus twisted pair, I happened to opine that many of the companies
putting in Category 5 thinking that they were being forward-looking were
likely to find that when they wanted to upgrade from plain-old Ethernet, the
technology-du-jour was likely to require something even better than Cat 5,
meaning they'd have to rewire ANYWAY.

In the Black Box catalog this morning (as I was leafing through it looking
for home wiring supplies ;-), I noticed that there is now a "Fast Cat 5"
cable which is rated for 155Mbps, with dramatically less attenuation at
~100MHz than Category 5 cable.  Presumably 100BaseT will be affordable
before 155Mbps is, but all around it looks like your best investment isn't
top of the line cables, it's conduit so that you can pull BETTER cables
five years from now...  ;-)