Dual-Boot

What kind of special hardware if any is needed to make a dual boot system?

Nothing really.

You need to partition your hard drive, but beyond that, it's not difficult.

or have 2 hard drives, but you dont NEED 2.

nope you don't NEED 2. i had an 80 gig split into 3 drives and had 1 each homework partitions for me and the wifey, and one dedicated to games... it was a little wierd to have to install everything 3 times but it worked for a long time... eventually broke down and got wife a laptop to get her off my box... (she kept downloading CRAP and somehow it would get on my installation too...?