Knoppix is a "live" CD, which means that the operating system (and loads of applications) is on a bootable CD. So you put the CD in your machine and reboot - in most cases a couple of minutes later it's running Linux. Without touching the contents of your hard drive, so no need to worry about repartitioning etc.
The downside is, of course, that running from a CD is slower than running from a modern hard drive. And being read-only, you lose any configuration changes you make when you reboot (there are ways around this, though).
Knoppix is a fantastic way to
1. Try Linux without committing yourself
2. Figure out what hardware you have (it has the best hardware detection of any version of Linux)
3. Rescue stuff from a dying, corrupted or otherwise unbootable hard drive - I've rescued sooo many Windows user's data that way...
You can get Knoppix from http://www.knopper.net/knoppix/index-en.html
As to downloading SuSE... I believe the latest version (9.3) is available from here
http://www.novell.com/products/linuxpro ... downloads/