DavidM, Running the 32-bit versions of those 2 programs you mention shouldn't be a problem in XP 64 or Vista 64. But indeed, if you can get a hold of the 64 bit versions you are better of... Since my switch to 64 bit (Vista Business 64) I didn't have any real issue. As opposed to 32 bit windows, you will have two 'Program Files' folders. One for 64 bit apps and a 'Program Files (x86)' folder for the old 32-bit applications. As an experiment, I even tried to install Sketchup in the 64 bit Program Files folder and it worked . But it still reacts as the typical old fashioned 32 bit app it is currently (low amount of RAM adressing, monocore only etc...).