How to restrict certain user name characters

[midnightz]

Hi,

We just searched the forums to see if there was hack or mod to make sure users cannot use certain characters in thier user names upon registration

such as a space, comma, period, / < { and so on...

The reason for this is that we have a uploader that is connected to the registration system and when users go to use those registered names with the illegal characters the uploader redirects them.

Lets say that if I signed up as Cool Kat that would be rejected and a pop up or notification would appear and some how state that a underscore should be used so Cool_Kat or CoolKat, would be acceptable.

This would help me greatly because I don't want the %20 and other weird html too be accepted.

Thanks, I'm a newbie excuse me if overstated what I'm looking for

Thank you,

midnightz