I have been Using Comodo Firewall Pro Alpha and Although the HIPS in the firewall is good but what a pain in the a** .
I mean c’mon if you are concerned that some virus1*.exe, trojan1*.dll, etc is hooking to some legitimate program there is a serious slow down of a system almost 77% cases and you open taskmanager and see what who are the culprits if the taskmanager is not showing what you want then why not try IBProcman http://www.spywareinfo.com/~merijn/downloads.html one of the best freeware program out there this program can show you what program is loaded what dlls.
hehe
and guess i have to click 10+ times just to open IBProcman.exe and i am using Comodo Firewall Pro Alpha 1.0.0.0 + Defense.
To answer your question. No. Its really not needed, but it couldnt hurt. If your already using CPF simply disable the HIPS. Thats more then enough protection.