Because I didn't want to take a chance and mess something up on the XP disk, I went into BIOS and changed the boot order so that the IDE is the first disk to boot. I then installed LinuxMint onto the second (IDE) hard drive (with GRUB). Rebooted and got the dreaded Error 17
Changing the boot order in your BIOS changes the hard disk numbering, (in most computers).
Since everything is so mixed up now, I think it would be the easiest to just set the hard disk order back the way it was originally and re-install Linux and let GRUB install where it 'naturally' wants to go.
Probably it will go to the second hard disk's MBR anyway, and if you get GRUB Error 17 again, just reverse the hard disk order in your BIOS. (After installing, not before).
Even GRUB's IPL does get installed to your first hard disc, (the one you have Windows in), GRUB won't harm your Windows installation because the MBR of a hard disk is not part of the Windows file system. By convention, no file system begins until sector number 63, and the MBR is sector number 0. Commonly, Windows boot sector is in sector 63, and that is the sector to leave alone.
You can control which hard disc GRUB will be installed to by selecting 'advanced', in step 7 of 7 during the Linux installation, and selecting it from a list, or typing something in yourself.
Otherwise, it's quite simple to re-install GRUB somewhere later on or run FIXMBR from a Windows XP recovery console.
I read your entire post and hope I'm being helpful.