Multiple Windows partitions?

Hello, I was thinking of possibly buying a Mac Mini to use as an HTPC, but I might be sharing it with my dad too (as a way to get permission to buy the mini), and we both use Windows for a few things.

The thing is my dad isn't that tech literate so I'm not sure I want to share the same Windows system with him (he just uses it for some old games, but sometimes he just starts browsing so I get paranoid what he might click on), so just wondering if it was possible to have multiple Windows partitions.

I searched through some old topics, but was never quite sure what to do. Based on what I've read, I think if I first use Bootcamp to partition the hard drive, then use Disk Utility to partition the Windows partition Bootcamp set up, then manually just stick in the Windows disc and boot from there to install, that might work? Or do I even need to use Bootcamp and I can just use Disk Utility to partition the hard drive into three (with the Windows partitions formatted as MS-DOS)?

I have an old copy of Vista lying around that I can give to my dad, while I'll install Windows 7 for myself (and it'll be easier to tell them apart too). And I don't plan on using either in a VM, so that shouldn't be a problem, I think.

Any helpful answer is appreciated, although I suppose I could just buy it and try it out, and if something goes wrong just reinstall Lion or something. And I think the return policy is 14 days, in case it doesn't work out? Still trying to convince my parents so I'm keeping the return date in mind.

And just to check, but I think Microsoft Security Essentials and the default firewall should be fine for everyday use, right? Not sure if I should get another firewall or not though.