Server Setup

[Manny]

I'm wondering if someone could help me out here. I want configure my
server with the following:

Apache
MySQL
PHP
Postfix
Samba

I know I can set these all up on one server, but I also want to setup
a DNS server. My question is should I use a separate machine to do my
DNS? Or is it okay to do it all on one machine? And is it okay to do
all of these on one machine?

Here are the specs on my server.

AMD 650MHz processor
35GB HDD
384MB SDRAM