Multiple OS system: basic architecture

I'm thinking about basically copying what this fellow is doing here (it's an AMD 8-core -based system).

But I want it to boot three operating systems: Windows 7 & 8, & Ubuntu. I would like to put the OSs on two different drives. Maybe Windows 7 and Ubuntu on one 1TB drive, then Win8 on its own little 32GB SSD drive. Is this possible? Will Windows "let" me boot 7 and 8 to a single motherboard, and will they update? I'm guessing that I would have to boot from the BIOS every time to choose from the different drives.

What about running my Windows 8 copy inside of Windows 7 as a VM in this setup? Is that possible? I think Paragon has software which lets you image an OS and then boot that image as an OS in a VM. I might run Chrome OS as a VM inside of one or several of these host OSs.

Of course, I'm open to suggestions as to how I might go about using a single nice and fast CPU/motherboard to boot multiple operating systems. The main thing is that I want to save some money and run Windows 7, 8, and Ubuntu on a single decent machine.

Thanks in advance,
Scott