Yonkey: The encryption doesn't really have anything to do with it, it's more a question if the bank uses things like ActiveX or IE-only javascript, or just simply uses a browser detection script to block out other browsers because they *think* other browsers can't handle it.
I got the feeling that the guy who wrote that post didn't state what was wrong with Safari's handling of the site because he didn't know exactly what was wrong.
Dew: If you dig around on the site, there's spec docs about the Firefox engine that seem to state that it can handle 128-bit encryption, but they're pretty geeky. You could try searching the Mozilla forums, or just asking yourself, that might work.

Peace & Luv, Liz