Maximum PC

Is there an app that I can use that would start before Windows (sort of like a bootloader) that would allow me to select which hard drive I want to boot from, and then disable the other drive so that the booting hard drive and OS cannot see it?
I know I can use the boot menu from the BIOS startup, but this won't automatically disable the other drives so that the booting drive cannot see/access them while running.

Any suggestions?

Reason for wanting to do this is that I want to run multiple OSes (each has its own physical drive) and want to be able to choose which one to use. Some of the OSes are used for testing, and may possibly get infected or corrupted (that's why I'd like to "hide" the other drives while the one OSes I've selected, is running--to not run the risk of infecting the other drives).

So use grub or lilo

and I think tools like easybcd will allow you to hide partitions too, but obviously that only works in Vista or 7.

I just used the easy way out, unfortunately, and just got a removable hard drive tray system with multiple trays. It's a big more physical work (of swapping drives in and out) but it will pretty much lessen the potential of getting viruses between the drives because the rack only holds one drive at a time (and my backup HDD is a USB drive is NOT always plugged in, so I only run with 1 drive most of the time anyway).

The only thing I have to concerned about is infecting other systems on my home network, but they are all protected with very good AV software and regular back ups so I don't see this really being a problem.