Help banning special characters on registering in vbulletin
 

I have read http://www.vbulletin.com/forum/showt...en-registering but still did not get it.

I want to ban users from using "£$%^&*(){}..... basically all special characters except . and - as these are are useful.

Can some one make me an expression for this? Also, will it affect current members, or just new ones?