It would be advantageous to use a RAID setup with your board, you wouldn't need an IDE disk to put your OS on then. But you would need to buy another identical 120Gb drive and then create a RAID 0 array.
Windows should then recognise the Raid array as one 240Gb drive (or maybe only 137Gb, not sure about Win ME) when you're installing. You'll need to install the Raid drivers for the OS when you're installing, not sure about ME, but with WIN 2K & XP, you put the floppy in the drive and hit F6 when prompted during the install. If in doubt, RTFM. Uh, that is, consult your Motherboard manual
Really though, for around forty quid you can pick up a 40Gb HDD to store your OS on, then access your 120Gb drive once Windows is installed.
PS: No need to shout Norton, all caps is considered bad etiquette old boy, and is not nice, no no. Patience, we is not all here online 24/7, somebody WILL get to you eventually though, 'k?