Installing Win7 64bit....
The standard 'safe' way to use 2 hard drives and 2 CD/DVD drives when using IDE devices, was to put one HD with the Windows O.S. on, on ribbon connected to 'IDE 0' on the motherboard. The BIOS is set up to find O.S there by default. Then on that same ribbon put one CD/DVD drive. The hard drive on this ribbon needs to have the jumper at the back set to 'MASTER'. Then the ribbon that is plugged into 'IDE 1' (on the motherboard), connects to your 2nd Hard Drive, that needs to have the jumper set to 'slave' or take it out altogether, no jumper required. On that ribbon you can connect your second CD/DVD drive. Note that it's the 'MASTER' Hard drive is where the Windows operating system should be by default. It will be called 'C' by Windows.
Boot the PC , press F2 and you will be in the BIOS. You now need to find the 'Devices' and the Drives section, and change the order to be; 1) CD/DVD 2)ON BOARD IDE OR SATA. The other options (USB etc) don't matter here. Put your Windows 7 disk in the cd/dvd drive., press F11 (save and exit). The PC will reboot, the new Windows disk will load some code and will look for any Windows OS already there. If found it will list it,
so now is your chance to let Windows FORMAT in NTFS. If your HD had Win98 on it, it will be FAT32, and XP could be FAT32 or NT. But if you choose 'Format in NTFS' the previous FAT 32 will be gone, (plus any files that were there). If your HD 'C' came from a 'shop bought' PC, it could have a small (say 5GB) partition, followed by 115GB, on your 120GB. You may as well delete the 5GB partition. You may need to create a new partition here for your own uses, e.g. 60GB and 60GB or as you require. Then you choose which one you want to install Win7 on (first partition) and it will format NTFS as it goes. All else is straightforward ! Note that you can do the partition work on the other drive, using a program called 'Easus partition wizard' or 'magic'. It's free and works well.
Your second hard drive will be called 'D' by Windows, your cd drives, E & F. If you have a media card reader in your PC, remove the leads from the back of it while you install Windows. Replace the leads after Windows is complete. Sorry if you know most of this, it's hard to judge how much anyone knows on 'posts' like these, but hope it makes sense !! In the BIOS you can change the order back to 1) ON BOARD IDE or SATA, or leave it as is, just don't boot PC again with WIN7 disk in. Good Luck.