How many connections at the same time could a FreeBSD server running a
Pentium 4 3GHZ CPU, 2 GB of ram, 1 TB SATA storage (5 X 200GB) with
access to 2 T1s worth of bandwidth... thanks!

I take your two T1's to have a total capacity of 3mbits. CPU and
bandwidth are the prime determinants. Assuming you wanted to give each
connection 56kbits of bandwith, you could host just over 50
connections. A 3ghz CPU will easily handle connections running over a
hundred.

I meant I have 1500 Gb of transfer available to me...  fully burstable
to 100 Mbit, I'm wondering how many accounts I should allow on one
server if selling hosting.

sorry I forgot to add, would it be much better to have a Daul Xeon set-up?

Xeon really just adds a higher cache to the CPU which only really aids
in intensive CPU bound applications. A web server really won't improve
performance based on a Xeon processor.

It's difficult to give a determination of how many connections that a
BSD server with those specs could handle since we don't know what kind
of applications will be running on it.

forge

It will be running Cpanel.net / WHM software and the autopilot billing software

control panel, dns, web, mail ftp, MySql etc.

Basic web serving functions... I can limit the load allowed by each user...

Thanks. Also is FreeBSD better then Linux at this?