Follow-up to Hacker problem

Your tips were nice, guys, thanks a lot. I tried a few things and i decided to go for making all the checks server side, cant go safer than that. Just have a doubt on one of the checks, at least so far. I have a check for long words, because the shoutbox is in a IFRAME, so if someone posted a long word, the infamous horizontal scroll bar would appear. How can i check for long words on a string and remove them before they get written on the DB? Thanks. Pag