But why do I need 5 partitions? Why can't I just partition it like so:

/dev/hda1 primary NTFS wnixp 5G
/dev/hda2 primary linux swap 500MB
/dev/hda3 primary linux 3G
/dev/hda4 logical linux 4G

I guess I'm still not understanding the function of the "extended" partition. Would it be just another drive that I could store stuff on, and you described it as "extended" because the size of it would simply depend on how much space is left after the other partitions are defined?