Great idea researching this first.
Big picture, is you can set up a system that boots the three operating systems--I just finished doing it myself. Mine is Win 98SE, Win2k and Mandrake 9.0 I do have some concerns about how you have outlined your plan, though.
Partitions 3 & 4. Swap them. For Linux to install, you will need to have some logical partitions and they belong at the end. Move everything from Partition 4 to Partition 3 and then delete Partition 4. Linux installs best when it encounters unused space, although Mandrake is pretty good at accommodating what is there.
Laying out partitions: There are tons of theories that you can spend time learning about later. For now, let's keep this simple and just let Mandrake set up what it wants.
First, validate your ISOs. You've already made the CDs, but let's still verify them. When you dowloaded the files, there were two other ones with them: Readme and md5sums.90. Go to this site and download fsum.zip:
Unzip it and put fsum.exe in the same direcotry that has your downloaded files. Type this command:
fsum -c md5sums.90
fsum will compare the files against what the md5sums.90 file says they should be. All three should pass. If one doesn't, download it again, check it and burn a new CD.
So, now you have three good CDs. Set your computer to boot from CD-ROM and boot from the first disk. This should bring up the Mandrake install program--it will look very different from its Windows counterpart.
When you come to the partitioning, it will take you to a screen that shows your current hard drive (it should show three primary partitions and some empty space at the end of the disk). Unlike Red Hats which offers you a plan right off the bat, Mandrake wants you to click your way through it. With your mouse, left click the empty space of the hard drive layout. This will bring up the add-partition window, which will offer to add a "/" partition and it should suggest a size.
Mandrake is not overly aggressive about taking up all of your hard drive, so its recommendation will be the minimum it needs. You can make this as large as you want, since you will only need a swap partition (about 500 MB) after this. I would suggest giving it at least 5 GB--more if you can spare it. (80GB hard drive, think about giving it 10-15 GB)
When you've finished with the add-paartition window, select OK. Next, add the swap partition--same as above. Mandrake will then step you through formatting the partitions. Make sure that only the partitions you added are formatted--do not format your Windows partitions (when I did this, Mandrake started with just the partitions that I'd added and did not select the Windows partitions).
Before you leave this part, look at what Mandrake is calling your very first partition--the one you have Win98 in. In Windows this is your C:\ drive. Note the name--you will need it later. For me, Mandrake called it win_c.
Your next hurdle will be configuring the boot loader. You have three options--the Windows boot loader or one of the two Linux ones (LILO and Grub). To make sure you don't have problems, I'm going to recommend you use the Windows ones. There is nothing wrong with the Linux ones--they are actually better. The problem is you are using an NT system--XP (along with Win2K) is an NT program. NT sometimes will check the MBR (Master Boot Record) to make sure a virus hasn't gotten into it. It expects to find its boot loader there. If it encounters Grub or LILO, it will refuse to start. Setting its boot loader up is a very easy two step process that I'll walk you through at the end of this.
For now, tell Mandrake to put its boot loader at the beginning of your first Linux partition. If you followed my instructions, that will be hda5. Linux numbers partitions this way: Primary partitions are 1-4 and logical ones are 5-15. Your first logical (where you put the "/" partition) should be 5. If you altered what I said above, you'll need to adjust this count.
That should get you to making a boot disk. You must do this. You will have to reboot Mandrake to do the first step in configuring the Windows boot loader and the only way to do this will be with a boot disk.
Hopefully, you are soon looking at Mandrake telling you that it is all installed and will exit its install program (shut down your computer). Let it do this and change the BIOS setup to now boot first from a floppy. Put the boot disk in and boot up Mandrake.
When you get to the log in screen, log in as root this time. Normally you do not want to do this, but you are only going to do one thing and you have to be root to do it.
When KDE has started you will notice several icons down on the left side of the menu bar. One looks like a monitor. If you move the mouse over it, it should describe it as a terminal. Click on this and it will open up something that looks like a DOS window in Windows. In Linux it is called a Shell or Terminal. You are going to create an image file with a Linux command. The basic command looks like this:
dd if=/dev/hda5 of=/bootsect.lnx bs=512 count=1
This looks complicated, but it isn't. dd is the command to make an image from the disk. if is for the input file (source), which is your hda5 partition. of is the output file. The rest just tells dd how much of the disk to grab.
If you were to type that command, it would create the file you need. Your setup, though allows us to save a few steps. Remember I told you earlier to note what Mnadrake called your C:\ drive? Probably, like mine, it called it win_c. That is what I will use for my example. If yours is something else, replace win_c with the correct name.
Most references for dual-booting with NT assume that your C:\ drive is in the NT format (NTFS), which Linux doesn't write to. So, they give you a process of writing it to a floppy and letting Windows copy it to C:\ drive. You don't have this problem. Win98 uses FAT32 at best, which Linux writes to just fine. So, we're going to modify the above command to write directly to your C:\ drive, which to Linux is /mnt/win_c. The command now looks like:
dd if=/dev/hda5 of=/mnt/win_c/bootsect.lnx bs=512 count=1
If this gives you problems (doesn't work too well or at all), use the first command and then move like this:
mv /bootsect.lnx /mnt/win_c
Anyway, reboot your computer (click on the 'K' in the lower left corner and select log out), removing the disk. Boot into Windows (either one will do) and start up Notepad. Open this file: C:\boot.ini
At the bottom of the file, add this line:
C:\bootsect.lnx="Mandrake 9.0 Linux"
Save and close the file. Reboot the computer and boot into Mandrake just to make sure all of the pieces are correct. Also, before you start, read this:
Report here if there was any problem. Good luck