I have used ISPConfig and VHCS also.
Let me save you a lot of pain. Avoid them both.
VHCS is so bad you can't even install it. After a couple of days of trying
to install, you will actually find that there are bugs in the install script so severe
that you have to patch them before you can install the thing. Basically, it only
works on Debian, and only if you dig through the internet to find the patch to the
install script. It is like your worst nightmare. Believe me.
ISPConfig was much better than horrible. It was just plain bad.
I was able to install it because I installed the pieces separately (ProFTP, named, MySQL,
Apache 2.2.2, and Postfix) and figured out how they worked first.
The manual is worthless. It basically says things like, 'Enter the IP address' next to the blank
for 'IP address', but does not say which IP address. The forums are useless. What you really
get with ISPConfig is the opportunity to have a lot of unexplained blanks on their PHP scripts.
You make your best guess about what these blanks might do, then hit "OK" and watch all your
conf scripts get nuked and your services go down. Then, when you try to restart your services,
you find the conf files in a unusable state.
It is much easier to read the following and do all the configuration manually for your hosting clients:
BIND: Read "DNS and BIND" by Albitz and Liu. It is old, but still works, except don't use nslookup.
Then get your free dns services from
freedns.afraid.org and avoid running a BIND server! Why bother?
Postfix: Read Postfix, The Definitive Guide, by Kyle Dent.
ProFTP is pretty easy to install and use in standalone mode.
Apache.org is awesome. That is documentation. Use httpd 2.2.2. Don't think about anything else.
php.net is awesome. That is documentation. With comments from readers. Avoid the Alternative
PHP acclerator, which is unstable.
MySQL 5.0 is awesome, and the online docs rock. phpMyAdmin 2.9 beta is good. The older ones
stink. But command line is still the best way to administer MySQL.
Maintain all the conf files yourself, and you will not be surprised. It is the Gentoo way.
ISPConfig is like walking in the dark. You're going to bump into something and hurt yourself.
Do you really like getting calls from users...Uhh. What happened to my site?