Our two new vista machines reject our company Small Business Server (SBS 2003 R2) certificate (used for OWA and Remote Web Workplace). None of our XP Pro machines have any problem accepting the certificate. Is this a Vista issue and is there a workaround?

Is the certificate form a 3rd party, or did you use the builtin on that came with SBS If you get a Warning when you use OWA and you click yes look at the certificate info ( ON URL line and see if if says Cert can not be verified by trusted authority) it mean you created you own certificate and you vista computer do not know that you did this.