Yes, with a little bit of trickery of the operating systems.

What you are lacking is the "boot loader" which is simply a small program on your C drive which is first to load when your computer boots, and simply gives you the selection of which OS to load. When you reinstall Win98/ME onto the C drive, it overwrites this "boot loader" and thus loses the link to the operating system on your other drive, and simply follows the pathway that boots your Win98/ME. Assuming the other drive is in tact, you should be able to get back to it by following these steps.

Note this may still corrupt or erase some data on your hard drive, so make sure if there is anything there, you have it backed up.

First, start normal installation of Windows 2000/XP from within your working Windows98/ME. Go ahead and choose full install, not repair. After it copies files, it will install the boot loader, and will ask to reboot your computer.

Choose your Windows partition, not the Windows Setup, and your Win98/ME will boot normally.

Go into My Computer, C drive, and make a copy by right-clicking and dragging the file BOOT.INI

Right-click on it then, and de-select Hidden and Read-only, hit OK.

Edit this file in Notepad (by either double-clicking or dragging it into Notepad).

You may wish to change the timeout from the default 5 seconds to whatever you like.

Change the default to Default=multi(0)disk(0)rdisk(1)partition(1)\WINDOWS

Add (or replace the setup option with) this line: multi(0)disk(0)rdisk(1)partition(1)\WINDOWS="Windows XP" /fastdetect
and save the file.

Reboot, and you should have your old Windows2k/XP and your boot manager installed properly.