I don't use online banking as I have no need to, living in a very small and compact town.

I do have a computer that is dedicated to online purchasing transactions. That is only used for that purpose, and for accounts that I have already set up. This is convenient for accounting and backup purposes, given that I have quite a few computers, and we have an organisation just as obnoxious as your IRS

If I ever do online banking, I would keep it on a "financial machine", more for convenience and control than security reasons.

You don't need anything exotic, and it is a good re-deployment of an older machine.

@ Aaron:

Longer passwords are stronger against being cracked..............that's just math............ there are plenty of attacks that don't require password cracking though.