I've tried out a few Linux(and FreeBSD) distro's through M$ Virtual PC on Windows, to narrow it down to maybe two or three that I want to install on my hard drive. To see how many I need to narrow it down to(and to decide whether or not to make two Windows partitions-one for the system stuff and one for my data), I'm wondering if its possible to boot Linux off of a extended partition. Also, I'm wondering if its possible(and how easy it is) to share a swap partition between multiple Linux installations, and if that swap partition could itself be an extended partition. Oh, also about swap partitions, I have a gig of ram, do I need to have a swap partition? Thanks in advance.

Yes it possible to boot linux if it is installed to a logical partition.
Yes you can share swap partitions between different linux installs
Swap can be installed on logical partition.

How much swap? With a gig of RAM you probably will never use swap but as a just in case I would go with 512MB.

BTW an extended partition in a nutshell is a container for logical partitions.
You only create one extended partition and then create as many logicals as you need to fill up the extended. An extended partition is a primary partition.

You can also have a boot partition and share it. That would make things a bit simplier when it comes to installing a kernel.

Entended partitions are only there because hard disk controllers (I think it's the controller, correct me if I'm wrong) can only handle about 4 actual partitions...so some chaps invented the extended partition to hold logical partitions of which you can have many more. It was basically just a hacked way of getting more than 4 partitions on a disk.

OK, I appreciate the quick help everyone