Triple Booting

Update: I successfully installed Zorin on the Bad Drive, alongside Windows. It installed perfectly, and did not affect Windows. In the process, I was able to solve the boot problem I was having with W7 on that drive. I had tried to repair it previously by inserting the W7 disk when prompted, but it never worked. I realized that if the drive would only boot from the vista drive, then the missing info must be in vista. Maybe because the machine came with vista installed? And W7 was an upgrade version. Anyway, this time, I attempted to repair it by inserting the vista disk, and it made the repair. So now, it boots off the drive it's actually on, instead of the vista drive. The weird thing is that when it starts W7, I first get the vista startup logo, as if vista is going to start. Then W7 starts. But it works. However, it still takes a long time to shut down, and comes up as BAD in Crystaldisk. Tomorrow I will see if it will install the windows updates that have been failing to install. Or, should I just call it good at this point, not push my luck?

I think you are doing OK - the Vista BCD is being used, I think because it preexisted the 7 installs. The graphical BCD bootmenu of Windows 8 and 10 actually reboots when a different version from the default in the bootmenu is selected. The whole boot process is like a separate mini OS that serves to get the main (selected) OS to load.

About the long shutdown time - is the pagefile being cleared at shutdown? This generally is not necessary unless you are concerned that remnants of the last session may be a security risk. There is a registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management
Value Name: ClearPageFileAtShutdown
Value Type: REG_DWORD
Value: 1

If the value is changed to 0, then the pagefile will be left alone. see https://support.microsoft.com/en-us/kb/314834

If you have sufficient free disk space you could try Imaging your Windows 7 installation, cleaning the partition and then reapplying the image.
Macrium Reflect Free is a popular solution, although the Windows Imaging system is perfectly usable from the command line. See Windows 10 - Setup and Run on USB Flash Drive - Page 2 - Windows 10 Forums for a link to get the WAIK (Windows Automated Installation Kit) tools (essentially Imagex.exe - see the main part of the same tutorial) without a big download. The imaging process strips Windows down to all the basic OS files, the registry, plus your programs and documents but dumps all the big files that can be recreated, like recycle bin, pagefile, hiberfile and restore points, as well as the hidden filesystem journals etc.

Finally, check your disks weekly to make sure there is no progression in the number of reallocated sectors. If the number is growing, the disk will fail sooner rather than later. If the number is steady, then the reallocations are just due to the disk firmware doing its job properly.

Thanks for all that great info, Fafhrd. To update the situation:
I decided to reinstall Windows (as an "Upgrade" so as to preserve my files). This was successful. I really thought doing this would solve the shutdown problem, as well as the update problem re: Microsoft.net framework updates. It did not, still had very slow (10 minutes!) shut down, and the updates would not install (although all others did). I figured then the problem must be with the drive. But the drive is actually stable, the reallocated sectors count doesn't change. So, I did some research. I wondered if the microsoft.net updates were the culprit. I tried repairs to no avail. Then I found something that said that this problem won't go away once you have it, and recommended uninstalling microsoft.net framework 4. So I did. Immediately, the computer began to shut down normally. I hid all the updates for it, and resumed other updates, eventually getting IE 11 so I'm pretty up to date. So, the culprit for the computer shut down issue, which has plagued this drive for years, was microsoft.net framework. With it gone, the computer (i.e. this particular drive) shuts down normally for the first time in years. I'm going to image it when it's all updated.
Now, the only question is, will it be Windows 10 ready? I did install the Get Windows update (KB3035585), but as of yet I don't have the little thingy on my desktop, although it did install successfully. The other thing I wonder about is, should I be worried that I don't have microsoft.net framework?

So glad that you got to the bottom of this!

I think that the Microsoft.NET framework 4 may be needed for you at some time in the future, if you so it may be worthwhile trying to reinstall it. First though, try to make sure all other windows updates are up to date, which you probably have done already.

I just updated my Windows 8.1 to .NET 4.5.2, so you might like to try to try 4.5 from the Microsoft.NET downloads page Download Microsoft .NET Framework 4.5 from Official Microsoft Download Center - I can't quite tell if 4.0 is required first, but the install will let you know. If you get slow shutdown after - you know what to do!

The official MS "GWX not working" answer is: I have the GWX.exe application, but when I execute it, nothing happens - Microsoft Community

Click Start

Type: view installed updates

Hit Enter

Look through the list for the KB3035583 update.

Right click it and click Uninstall

then reinstall it through Windows Update:

(https://support.microsoft.com/en-us/kb/3035583)

I needed Microsoft.net Framework sooner rather than later! I needed to install Easy BCD on this drive, and sure enough it needs MNF to run. So I took your advice, Fafhrd, and installed 4.5. Installed perfectly. And Easy BCD as well. AND my computer shuts down faster than before. AND it is Windows 10 ready. How cool is that? Thanks again, Fafhrd, you've been a big help to me!

Cool indeed! Glad you sorted it all out. :)