in the last week or so...
i think i've done over 10 installs just trying to get things rolling.
i've ran into this same problem, and i share your frustrations.
however my fix was quite simple.
after you prepare your system via howtoforge guide
do not follow the patch found @ http://dev.dyslexification.com/
rather use the method that TILL suggested to successfully install ispconfig on centos 4.4.
There is a easier solution to install on centos 4.4 then using a patch.
1) Make a backup of your /etc/redhat-release file.
2) Change the version numebr in the redhat-release file to 4.3
3) Install ISPConfig.
4) Restore the backup of your redhat release file.
that gave me a working server the first time.