The method from the poster above definitely won't work. It's best to put both operating systems on the new hard drive, and make the old hard drive entirely logical partitions. If you really want one operating system on each hard drive, then don't set a primary partition on the second hard drive; make it entirely logical partitions. Then put WIN2000 on a logical partition of the second hard drive, while of course the active partition is still drive C (that is, the partition with WINME installed).
There's another method: use the multi-system partition software magic partition to create two C drives (one visible, one hidden), and install ME and 2000 on them separately. When booting, it will let you choose which primary partition to boot. When you choose one of them, it will hide the other one. That way there won't be any drive letter mix-up.
Actually, drive letter mix-up is mainly caused by having multiple primary partitions.
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