Firefox CSS – Spacing incorrect

Trying to create a CMS type site for a local non profit:

http://www.healthnetoswegocounty.org

Looks fine in IE6. Firefox the sidebar’s right margin is outside the page margin.

Put it through here:

http://validator.w3.org/check?uri=http%3A%2F%2Fwww.healthnetoswegocounty.org%2F&charset=%28detect+automatically%29&doctype=Inline&group=0

Nothing appears to me as the cause of the problem. Do I have to fix everything it mentions? It’s mostly missing alts and comments it is catching.

Thanks.