Opera can impersonate IE5 pretty well and as Adam says "via a nice pointy clicky interface" so its real easy to change. It also does Netcape(Mozilla) 5.0, 4.6 or 3.0.
I used Opera 5 for a while, but during some testing on a web application, we found it did not handle post/get requests from forms correctly. The cause of these issues could be numerous, but I thought I would mention it as a note of caution as you may be using it for online banking purposes. Run some test cases first.
Ashley