Steps are common for Windows Vista and Windows 7. 

 

Method 1.
a. The Internet Explorer shortcut in the Quick Launch toolbar and in the Start menu of Windows 7 x64 will run the 32-bit version of Internet Explorer by default.
b. There are actually two shortcuts for Internet Explorer in the "All Programs" menu.
c. Here's the title of each and the exe's they run:
d.
Internet Explorer 32 bit
"C:\Program Files (x86)\Internet Explorer\iexplore.exe"
Internet Explorer (64-bit)
"C:\Program Files\Internet Explorer\iexplore.exe"

The first one runs IE from the "Program Files (x86)" folder, this is the 32-bit version. The second one is the 64-bit version.

 

 

Method 2.
If you want to change the default internet explorer from 32 bit to 64 bit you may perform the following steps.
You can change the program windows uses by default to open with different file extensions.
Here is how:
a. Click on Start and go to Default Programs.
b. Click on Associate a file type or protocol always open in a specific program.
c. Browse to all the extensions where internet explorer is set as default and then click onchange.
d. Now Click on browse and then go to location C:\Program Files\Internet Explorer\iexplore.exeand select it.
e. Click Ok and then Close.
f. Click Save.