You may already know about this but I am getting the following error from the SSL Cert on ispbin.com when hitting your donation link:
Secure Connection Failed
uses an invalid security certificate.
The certificate expired on 03/04/2008 1:06 PM.
(Error code: sec_error_expired_certificate)
* This could be a problem with the server's configuration, or it could be someone trying to impersonate the server.
* If you have connected to this server successfully in the past, the error may be temporary, and you can try again later.
I don't know if this is even your responsibility as it's an outside merchant. I deal with this quite a bit at work - generally most people would ignore a popup error in the IE 6 and FF2 browsers but both IE 7 and FF3 totally stop the page load and you have to make an exception to load the page.