*warning* These instructions assume that you want to completely erase your drive!!!
I think the easiest way to clear out the old system entirely would be to get a copy of a Knoppix cd or even somthing like the bootable Gentoo install CD. (I have never done this wich a Knoppix cd, so I don't know for sure if it has all the tools you need. I know for a fact the Gentoo cd does though. Look at www.gentoo.org
if you need to download an ISO of it.) Boot off that cd, and find your way to a command prompt.
The next step is to find out which drive you want to erase. If you only have one harddrive in your system, it should be /dev/hda. type "cat /proc/ide/hda/model" to make sure you know what drive you are dealing with. If hda doesn't work, try ../hdb/.. or ../hdc/.. in that fashion until you find your drive. My harddrive is hdc and /model says somthing like this:
root@tcm # cat /proc/ide/hdc/model
Once you have found your drive type in "fdisk /dev/hda" where "hda" is the 'name' of your drive. Type "p" (for print) when prompted for a command and you should see somthing that resembles this:
root@tcm # fdisk /dev/hda
The number of cylinders for this disk is set to 9729.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Command (m for help): p
Disk /dev/hda: 120.0 GB, 120025313280 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/hda1 * 1 9 72261 83 Linux
/dev/hda2 10 259 2008125 82 Linux swap
/dev/hda3 260 9729 76067775 83 Linux
Command (m for help):
You're almost done!
Now just type in "d" as your command (for delete) and when prompted for a partition to delete say 1. Do the same thing again and for the partition, say 2. Keep doing that until there are no partitions left. (You can check this by doing a "p" command now and then.) Now, type "w" (for write) as your command to write the partition table to the disk. You're done! You're old linux install should be history. Reboot and enjoy installing your new distro!