The only way you'll get hacked is if someone does a Mission Impossible on you.
I'm afraid you are just deluding yourself.
It was a joke. There`s a continuum of risk. I don't think it`s as binary as you suggest. I`m not saying it replaces common sense or other sensible precautions. And, yes you can still get hacked. But physical separation along with the other things we all do sig. reduces exposure to rogue code. IMHO
If virtualization still isn't enough for you (and it shouldn't under most configurations - a VM is only as secure as its host, it'd be better to sandbox the risky stuff than the banking), it's still just as secure (if not more so) and cheaper to boot into a Live CD or USB install of Linux on your pre-existing machine than it is to purchase a dedicated one. The only risk then is BIOS level viruses, which are rare.
Honestly Mr. Mark, there's only so much risk mitigation you can do, and although I don't doubt for a second that your heart is in the right place, your logic is not.
This is what I'd call Howard Hughes security. It's where someone is so wrapped up in their fear of germs that they wear kleenex boxes for slippers and store their urine in jars and
completely miss the fact that they're wearing kleenex boxes as slippers, they're storing their urine in jars, they've turned the carpet black and are growing entire ecosystems under their uncut fingernails! It's simply misdirected overkill to mitigate risks that aren't even your biggest threats and concerns in the entire chain. Honestly, doing
anything online with finances is like playing Russian Roulette with a million chamber revolver; you either accept the risks and safeguard against the worst case scenario, or you don't. Quite frankly, if you knew what I do about network security and infrastructure, with the approach and mindset you're taking, you'd never bank online again...
...or buy anything online...
...or use credit/debit cards in general...
...or ATM machines...
...you'd keep nothing but non-sequential bills hidden under your mattress, pay cash for everything and sleep with a shotgun. The more you know about networking, the more you realize you have to trust your poorly encrypted traffic to more groping hands than you'd find in a giant filthy orgy. (Sorry Sparafusile, I wouldn't do Tor for financials if my life depended on it. Too easy to honeypot an exit node, amongst other issues with the network. Tor is "anonymous", not secure.)
I'm not saying you shouldn't execute security best practices, and if you're so clumsy and careless with security that it keeps you up at night unless you have a dedicated machine for transactions... if it helps you sleep better, sure, but understand it's a placebo. Far bigger threats lie between your modem and their servers. Staying properly patched and updated, not running your account as admin/root, running behind a hardware firewall, using a decent AV program, downloading and installing applications only from authenticated sources, using strong passwords and keep them in an encrypted database if you need them written down, using a web browser with whitelisted sites for plugins and ads (Firefox with NoScript and AdBlock+ for example), staying away from the filthy back alleys of the internet, not keeping cookies, using a dedicated e-mail client in plain text mode, not participating in social media fads, being aware of social engineering techniques, and just not being careless about where you go online is about as secure as you can really hope for with
any networked computer. The exact same risks would exist on a machine maintained that way as they would on a dedicated for financials only machine, and if anything, is most likely
safer because you're actively maintaining the machine for security in general instead of only turning it on to do your banking once every couple weeks.
tl;dr: If you still insist on being paranoid about something, be paranoid about your DNS servers, your ISP, your bank's security practices and public servers, your bank's employees who insist on bypassing the firewall and playing some idiotic Flash game linked off Facebook on their workstation during their lunch break, and the quality of the "randomly generated" salt tables for your encryption... then realize they're all things that are nearly entirely out of your control and the best thing you can do is just keep up your own housekeeping.