Okey, i'm now running modsecurity 2 with owasp 2.7.1 Rules.
For those who want to protect their servers against WEB attacks on a Debian Squeeze read the following Manuals.
First (remember to change the paths in some commands, CHECK IT)
Second, download and install (follow INSTALL file inside the .tar) the rule set from
Third (Optional) - Bann Attackers with iptables