Apache

Run

apt-get install apache2 apache2-common apache2-doc apache2-mpm-prefork apache2-utils libapr0 libexpat1 ssl-cert (1 line!)
apt-get install autoconf automake1.4 autotools-dev libapache2-mod-php4 libkrb53 php4 php4-common php4-dev php4-imagick php4-mcrypt php4-rrdtool php4-sqlite php4-curl php4-domxml php4-gd php4-imap php4-ldap php4-mcal php4-mhash php4-mysql php4-odbc php4-pear php4-xslt (1 line!)

<- Yes

Edit /etc/apache2/apache2.conf. Change

DirectoryIndex index.html index.cgi index.pl index.php index.xhtml

to

DirectoryIndex index.html index.htm index.shtml index.cgi index.php index.php3 index.pl index.xhtml

Edit /etc/mime.types and comment out the following lines:

#application/x-httpd-php                                phtml pht php
#application/x-httpd-php-source                 phps
#application/x-httpd-php3                       php3
#application/x-httpd-php3-preprocessed          php3p
#application/x-httpd-php4                       php4

Edit /etc/apache2/mods-enabled/php4.conf and comment out the following lines:

<IfModule mod_php4.c>
#  AddType application/x-httpd-php .php .phtml .php3
#  AddType application/x-httpd-php-source .phps
</IfModule>

Edit /etc/apache2/ports.conf and add Listen 443:

Listen 80
Listen 443

Now we have to enable some Apache modules (SSL, rewrite and suexec):

a2enmod ssl
a2enmod rewrite
a2enmod suexec
a2enmod include

Reload Apache configuration:

/etc/init.d/apache2 force-reload

Proftpd

apt-get install proftpd proftpd-common ucf

<- standalone

For security reasons you can add the following lines to /etc/proftpd.conf (thanks to Reinaldo Carvalho; more information can be found here: http://proftpd.linux.co.uk/localsite/Userguide/linked/userguide.html):

DefaultRoot ~
IdentLookups off
ServerIdent on "FTP Server ready."

and restart Proftpd:

/etc/init.d/proftpd restart

Webalizer

apt-get install webalizer

Install some Perl Modules needed by SpamAssassin (comes with ISPConfig)

apt-get install libhtml-parser-perl libdb-file-lock-perl libnet-dns-perl

On To The Next Step...

The configuration of the server is now finished, and we go on by installing ISPConfig on it.