You can no longer draw pipe or HVAC in our AutoCAD MEP using a Windows 7 64bit machine and now get this error message:
Error: There is a problem with the Script Control (msscript.ocx). This problem may be corrected by reinstalling Internet Explorer or by registering the control.

First I followed Josh Benoist steps from this blog posted with SOLVED but I still got the error message. There is an attachment in the blog so make sure you go to the blog and download the zipped folder. Here is what Josh has as the solution to this error:
Good news. We have been working on this MSscript.ocx issue.
We recently discovered the cause and developed a solution. Would you please have a look at folder: C:\Program Files (x86)\Common Files\Autodesk Shared, and verify the existence of the following files.
Aec32BitAppServer.dll
Aec32BitAppServer57.exe
Aec32BitAppServer57.tlb
If missing please find the attached zip file, unzip and copy the above 3 into the above location. Next, let's import the attached registry settings file. To import registry, save the txt file attachment to your desktop, rename the txt file's extension to .reg, and then double click on it. That will fix the registry. Go ahead and test for the MSscript.ocx error to be gone. Please let us know your impression on the above material and if this helps. Have a great day.
Joshua Benoist, PE Senior Support Specialist Product Support Autodesk, Inc.
It wasn't until I followed these steps from this blog I found in the Autodesk forum community that my error was fixed.
The user who had done these steps below said that it did not work for him but when I did the steps it worked for me. The one thing I did not do is install the Microsoft script control and I did not uninstall Internet Explorer.
1. Go to Start All Programs Accessories.
2. Right-click Command Prompt and choose "Run as administrator."
3. Enter the command:
Regsvr32 C:\Windows\SysWOW64\msscript.ocx
You can copy and paste this by right-clicking in the command prompt window to do the paste.
4. Click OK on the message that says the file registration succeeded.
5. On the keyboard, hold down the WINDOWS key and then hit R.
6. In the Run window, type REGEDIT and then click OK.
7. Find the following folder:
HKEY_CLASSES_ROOT\TypeLib\(0E59F1D2-1FBE-11D0-8FF2-00A0D10038BC)\1.0\0\win32
8. Right-click the win32 folder and choose "Permissions."
9. Make sure the administrator group has full control.
10. With the win32 folder selected, make sure the (Default) key at the right is set to the following path with no quotes around it: C:\Windows\SysWOW64\msscript.ocx
11. Close the Registry Editor.
I cannot confirm if doing both solutions was the fix but I assumed that Josh Benoist post was regarding 32 bit machines and the second solution I have is regarding 64 bit machines.
Either way these were the steps I took to solve this error message without having to a reformat of my operating system like so many post said they ended up doing.