AFAIK there aren't nor has there ever been any bugs in IE's SSL implementation. I've never heard of anyone exploiting an SSL transaction. Breaking in to someone's "secure" server, yes. Intercepting and decoding SSL-encrypted traffic, no.
I think you can use IE6 with total confidence to do your online banking - assuming your bank has their security properly set up. And NO browser can control that, it's all on the server end of the pipe.