I would like to set up two separate boxes:
1) web server (mostly a personal photo gallery), file sharing server
2) mail / POP3 server (~100 users), streaming video server (1 user limit due to bandwidth restrictions)

I would also like to throw DNS caching on one - but it doesn't matter which one. I don't see a real benefit to putting it on both, or is there?. I'd use that machine as my primary and then my ISP's as secondary.
I have 2 boxes:
1) Celeron 433
2) Athlon 700

I have about 384 MB RAM for each machine and I guess that I *could* buy more if needed.

Question - which services will require more processor time?

Thanks!

Just a guess, but I would imagine that the mail / POP3 server will use more resources than the other.

Either way, they should both run fairly fast as long as you don't run X.