You didn't mention why the HD wasn't bootable as in is really screwed-up or simply a h/w and/or OS fault. If the orginal HD can be mounted and you have access to another HD, install the replacment HD as drive C and the old one as drive D, or as the new master/slave setup. I assume you know how to do that. The new HD boots up and if the old HD is at least mountable, you can transfer data. I exclude any h/w fault or virus/malware at work here. If you find the data is hosed, then I have no cure even if old HD mounts. If the data is small amounts, try booting with a startup floppy and see if even you can access the old drive C and possibly the data. You can try a s/w HD repair, check at http://www.grc.com and find "spinrite" pgm. provided no hard fault is present. Also, similar pgms. like Norton "disk doctor", etc. may help.
Try the sys command. Just as SYS C: which will reload the MS bootable command back to the drive, if capable. The startup floppy or OS cd. If XP, see if the "repair"
HD works, but try that if the above does apply.
Later, for using the computer to the scout troop, you can buy a "swappable" HD kit. You can then physically remove drives as in "swap" with computer off. Keep your important HD for your own needs when done, take it out and replace it with spare HD that the scouts can call thier own. Hope all this helps -----Willy
I would like the ability to boot a second hard drive on my PC. No, I don't mean dual boot. I mean REALLY boot another hard drive, with the regular C: drive not required.
Most people I discuss this with immediately ask, "Why would you want to do such a thing?". Their question is so automatic, I'm amazed. I come from the VMS world where this capability has existed and been used extensively over 30 years. If you already understand why I want this "bizarre" capability, skip the following numbered reasons.
1. My C: drive has just become unbootable and I want to boot another hard drive with all my debugging and repair software. Maybe I can find the problem and fix it without reinstalling Windows and reconfiguring everything. Then I can recover that critical file I didn't back up.
2. I have a new operating system beta from Microsoft and I would like to try it before installing it on my production C: drive. And I don't trust MS to roll back to my currently stable and working operating system WITHOUT any change whatsoever.
3. I turn my computer over to the local Boy Scout troop every Saturday morning. I don't want them working on my regular hard drive. Instead, I want to give them a hard drive of their own, totally independent of my hard drive and any changes I may make on it.
Are we clear? Hard drive C: is dead, gone, isolated, off, unplugged, or just hiding its head. I want to boot drive E: and get a full Windows 2000 operating system.
A suitable alternative is to change the name of hard drives (or partitions thereof) so that what was drive C: is now (say) drive L: and drive E: turns into drive C:.
I have never found anyone who knows how to do this on a PC but I suspect it may require a new or updated BIOS. Is this true? If I appropriately update my BIOS will I be able to install a full free-standing Windows 2000 on my E: drive? And then can I boot drive E: with the control cable disconnected from drive C:? Or is there another viable approach?
Can I restore a backup of my C: drive to my E: drive and then boot the E: drive? I realize this may may add a problem if the restore software doesn't leave a boot block on my E: drive. Any suggestions for how to built a boot block on drive E:?
What about partitions on the second hard drive? If I have it partitioned as drive E: and F:, can I boot either one (assuming each has a working operating system)?
Can I put Linux on drive F:, Windows 95 on drive G: and MyOwnOS on drive E:? And will each of these operating systems have the potential to read/write all other drives on the motherboard?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic