[resolved] Spam bots

[DAMINK]

Ok were all used to spam bots. Xrummer and the like.
Now i am new to vBulletin but the one thing i did notice immediately once i merged my MyBB forum over to VB was how easily spam bots were able to register.
I can only assume this relates to some vulnerability in VB?
Given they can read Captures, Random questions and the like.
So i started the battle to defeat the buggers as we do.
First i added the proxy script to help a little.
I then added additional registration requirements.
Most recently i added the mod which puts a timer on the registration process. This actually works quite well. However they are still trying to register constantly.
So this go me to thinking. There has to be a better way to stop these buggers.
Now here is my thoughts on it. Tell me if its a good idea or a stupid one please.

First rename register.php to a new name.
Change all links from the forum to point to your new page.
Then recreate register.php but make it a bot trap only now and nothing more writing to the .htaccess file and ultimately banning there ip the moment they trip the trap.
Making sure your robots.txt file is up to date to reflect changes obviously.
I assume xrummer and other tools are using vb as the target and therfor using register.php as the default register page.
Its clear they can beat the capture and other options so i think there really is no option but to make it harder.
Anyway thats the basic idea of what i want to do.
I have mostly finished it. But i have one problem currently and need some help.
I have only edited the old register.php file and renamed it currently. The bot trap bit i have no problems with.
I can register using the new file fine however at the last point of registration is sends me back to the original register.php file. Now if i can remove this then i am home free i think.
Anyone have any ideas how to stop it redirecting back to register.php?do=addmember and have it go to MYFILENAME.php?do=addmember?
Finally could this be a security issue itsself trying this?
Thanks.