validation to check if any boxes ticked

[kapow]

I have a form with about 20 tick boxes and I need a simple validation to make sure people tick something. There are also some text input boxes on the form but it doesn't matter if they are used or not.

Can anyone tell me the JS to do this:

if (no boxes ticked) {alert 'You must select something'}

[CaseyRyan]

I just posted a javascript piece that does this:
http://www.webmasterworld.com/forum91/3330.htm [webmasterworld.com]

-=casey=-

[kapow]

Thanks
I just put my reply in that thread too.