Network Sizing Guidelines?

[Daniel R Glover <Daniel.R.Glover () grc nasa gov>]

Can you point me to some current network sizing advice for Internet service 
(WAN and LAN)?  I am looking for rules-of-thumb, guidelines, equations, 
books, or even anecdotal evidence that would help me in evaluating future 
network design concepts.  I have somewhat unconventional network 
constraints, but I would like to start from current conventional 
assumptions on, say, numbers of users (home or office) that can be 
supported by various bandwidths.

I've tried the related links off the NANOG pages, but some are old or 
broken.  I have found some advice like "a T1 will support 200 to 300 28K 
modem users," but I hope there may be more current advice somewhere 
especially with regard to QoS, future trends, and to larger networks.  Any 
relevant pointers or advice would be welcome.

R/
Dan Glover