building a distribution server

[Steel City Phantom]

i have about 10 production servers that i want to upgrade to bsd 7 and
update all their ports in one shot.  the problem is the down time.  im
wrapping up upgrading a 6.3 to 7 and its taken over 7 hours so far.  thats
way too long for our machines to be down.

the biggest slow down is the downloading of files.  just sitting watching
things i would say 70% of the time is downloading files.  is there a way
where i can build a distribution server that has everything i could possibly
need to upgrade a machine from any 6.x to 7.0 and redo all the ports on that
machine and have a cron job keep everything up to date on that server and
when i upgrade a new machine, it simply goes to my internal distribution
server to get the files.