True. You can have more partitions that aren't primary. My Slackware Free BSD dual boot box has 3 or so primary partitions, then add to that about 10 non primary partitions.

If you REALLY want 5 OSs on your computer.... Well, you're not using a laptop. You need something with multiple HDs in it. I have software here that allows me to use 100 or more OSs on a single system. I know people have done 100 or so at least before because I've seen it. But you're going to need more than one HD.

My personal record of OSs booting, is on this box, which I had Windows 98 SE, Free BSD, and Mandrake Linux on.