There is a much easier way to determine if you can use 64-bit if you already
have Vista 32-bit installed.

-Right click on My Computer
-Choose Properties
-Click on Windows System Performance Rating (you may not already be rated,
so follow the prompts to do the rating).
-Once the rating is complete, click on View and Print Details
-In the printable menu, it will state 64-bit Compatible:

Viola, you have your answer!

BEidsvold