Stopping spaces being used in names

Hi guys,

We have a common problem with people entering their name but putting a space after their first name. Meaning that there are two spaces between the first name and second name, so when you're trying to tag people if you don't know they have done this then you will not enter two spaces between the name to tag them. So it looks like the user doesn't exist? How can we stop spaces being entered into the first name and second name boxes and it really doesn't work well with tagging.

Thanks
Katie