Online banking sites that are not keen on Safari work fine with the others, and the Mac comes with IE.
I run Firefox on my Macs, and it's better than Safari for online banking. I've only ever seen one problem, which is a very minor rendering problem with First Direct's banking client (it's still fine, just looks slightly odd). I've never found a reason to use IE on the Mac.
I have VPC, but it's a bit of a dog even on my 1.8GHz G5 with a 1.5gigs of memory and i've been moving away from it. Word, Excel etc. are available in native Mac versions (which are very nice!) but I must admit to keeping a PC for a few other bits and pieces that just don't work well enough on VPC...
