I am thinking about switching to Mandrakelinux

Your best bet would be to install another harddrive (hdb) and install linux on it. Install the boot loader, most likely LILO or GRUB, on the mbr of the first harddrive (hda1), the boot loader should automatically detect Windows and add it to the boot options. Otherwise, you will need to resize the Windows partition, to free up space for Linux, partition the freed up space.

Mandrake includes a newbie-friendly utility for resizing your Windows partition. I used version 10.1 which does support the NTFS filesystem and had no problems at all. The bootloader is right there, along with many choices of program packages.

I do have a very small hard drive on my DimV400, of course. You should definitely back everything up first just to be on the safe side.

I would also like to recommend that you try a Live CD before you make any changes to your hard drive that you might regret later. The hard drive install may have more features, but you can get a taste of what Mandrake is like by booting from the Mandrake Move CD and playing around for awhile.

Slackware also has a run-from-CD version you could try out, as do many other distros. Dell Bios has a minor issue with Knoppix and Knoppix-based CDs but all I've ever had to do is unplug the power cord from my Dim4550 for a minute before I boot back into Windows after a Linux session.