There is a way to trick Windows into using 64-bit in all circumstances. It involves using the NTFS file system's inherent feature called symbolic links (also called NTFS junctions). A symbolic link appears to Windows and any programs running in Windows as a real directory but is, in fact, a pointer redirecting the program to another drive or folder. Windows uses symbolic links to maintain backward compatibility. For example, in Windows 7, there is a hidden symbolic link in the root directory entitled “Documents and Settings” that points to the “Users” directory in order to maintain backward compatibility with programs written for XP (turn off “Hide Protected Operating System Files” in Folder Options and see for yourself—after looking, don’t forget to turn it back on!).
Sidenote: I use symbolic links to relocate all of those unwelcome folders in My Documents created by various programs. I did a write up on that here.
Here's how to make 64-bit IE your default browser in all circumstances. Note, following these steps will disable 32-bit IE. However, it is simple to switch the default back to 32-bit when a page must be opened in 32-bit.
1. Go to www.sysinternals.com and download the Junction application (Note: Sysinternals has a plethora of great apps worth checking out). Save the executable somewhere easy to find, like the root of your hard drive (i.e., “c:\”).
2. In Windows Explorer (with IE not open--so print these directions), rename the “Internet Explorer” directory in “c:\program files (x86)” to “Internet Explorer 32bit”.
The 64-bit version of IE is located in the "Internet Explorer" directory in "c:\program files". We are going to create a symbolic link at "c:\program files (x86)\Internet Explorer" that redirects to "c:\program files\Internet Explorer". This will cause all programs--including Windows--to run the 64-bit version when they go to what appears to be the folder at "c:\program files (x86)\Internet Explorer" but what will be, in fact, a symbolic link. (Note: One can quickly change the symbolic link to point to the "Internet Explorer 32bit" folder that contains the 32-bit version. I use scripts to allow me to quickly change the default back and forth).
3. Open an elevated command prompt. To do so, in the Windows Search box, type “cmd”. Right click on “cmd.exe” and select to “Run as Administrator”.
4. At the command prompt, navigate to the directory in which you saved “junction.exe”
c:\Windows\system32> cd c:\
5. Type the following command:
Junction "c:\program files (x86)\Internet Explorer" "c:\program files\Internet Explorer"
If you want to change back to 32-bit, just type the following two commands at the elevated command prompt:
Junction -d "c:\program files (x86)\Internet Explorer"
Junction "c:\program files (x86)\Internet Explorer" "c:\program files (x86)\Internet Explorer 32bit"
The first command is necessary to remove the existing symbolic link before creating the replacement one.
That's all there is too it. As I said above, one can create scripts (batch, powershell, or vbs) to make switching back and forth easy.