I also have a considerable number of mission-critical Windows-only apps. But for me, running Windows (XP and Win7) in a VM is -perfect-, because it's trivial to correct errors, corruption, BSODs, whatever -- just replace the VM with the most recent copy, takes about a minute and no effort. Beats screwing around with restore/reinstall hands down. Not saying it's for everybody, but for me it's great.
I run VMWare Fusion on my Mac. XP rarely crashes that way (runs really fast, too) and I can run the good version of QuickBooks. Best of both worlds.
Ah, virtual machine snapshots. They've saved me many times. Fusion does these great.