If I understand it you just want to set up your new HDD as your main boot drive, install win 2k on it, install all your other programs on it, and finally copy over your MP3 data files to it. After that you may not even need the old HDD, or you can use it for backups - whatever.
So try this:
1. Before you take the old system apart (!) prepare a bootable DOS floppy (use "sys a:" to do that) also containing files fdisk.exe and format.com. Try to prepare the bootable floppy from the same OS you will be using on the new HDD. And test it.
2. Setup the new system's hardware, but just put in the new HDD, not the old. If I've got it right all you want off the old is your MP3's. Worry about them later, after you're up and running with an operating system. Too many HDD's spoil the setup. But I guess it doesn't matter as long as you keep track of which drive is which when running fdisk.exe and format.com (see below)!
3. Start the PC and boot from the floppy from step 1. Type "fdisk" at the prompt and when fdisk starts follow the prompts to partition the disk as you wish.
4. Next use format.com to format each partition that you've created in step 3.
5. Now install the operating system and applications. This is where you may want to use the utility that comes with the new HDD to transfer everything over from the old drive (including the MP3's). But a clean install is always nice too. Either way install the OS and apps. BTW, a clean install of Win 2K, not an upgrade from Win 98, is to be preferred, especially with the nice system you'll have, where you'll want to minimize bugs. A good rule is no more than 1 upgrade with stuff like MS Office, and no upgrade when going from Win 98 to Win 2000.
6. Finally, if you haven't already, install the old HDD (resetting jumpers if appropriate) and transfer the MP3's to the new. Also transfer any other data you want from the old to the new drive.
7. Then reformat, partition etc. the old HDD to suit your new system's needs. I use my old HDD for backing up all my data, and keep it disconnected between backups (they make removable HDD caddies for this purpose too). But come to think of it - you may not want to reformat the old HDD until you're sure you have all the data from it that you might ever want.
Also, before you start, check the instructions that come with the drive and review the zdnet link I gave you above.