in your bios set the cdrom to be bootable and set it as your first boot device.
boot up with your win98 boot disk. only select boot computer with cdrom suport. it will bring you to a command prompt.
type fdisk
you will enter the fdisk utility...now if you dont have anything on your HDD that you want to keep then wipe the entire thing out and create two dos partitions equal in size.
now reboot with the win98 cd again and format each partition with the format x: utility this will format them into the fat32 format.
now reboot with the cdrom again but this time setup up win98 instead of starting the pc w/wo cdrom. install win98 with all the options you want. it would be way too much to ask to have us explain every last option, its pretty self exlanatory.
after youve installed win98 install all of your drivers for your device, ie video sound nic/modem etc...
then when in win 98 pop in your windows 2000 cd and go through the initial setup options. make sure you look into every possible option so you dont miss something. you do want to make sure that you select "Let me chose which partition to install windows" option. that way you can install win2k on your second partition. make sure youdont use NTFS on the second partition, leave it at fat32. if youve accidentally formatted to fat16 you can convert it to fat32 within the win2k install.
install like normal, drivers etc... and you should be up and running...im sure youll be back here asking questions....so i recommend you use the search features of these forums and also do a search on google.
good luck.
loosbrew