With the announcement of Windows 7 more and more systems will be delivered with the 64-bit edition.
The most important advantage of 64 bit versus 32 bit is that you can use more than 3.5 GB in your system. If your computer at the moment is equipped with 4 GB you can only use 3.5 GB for your system and applications. With 64 bit versions either Vista or Windows 7 you can use above 4GB.
Your processor has to have 64-bit capabilities.
I have tested several versions especially with the focus on speed. Windows Vista and Windows 7 were tested in 32 and 64 bit on an AMD Turion64 X2.
My focus was looking for difference between the feeling of speed and working speed.
Editting a Full HD 1080p recording with adding 3 effect in Adobe Premire Elements 7 (32 bit version).
I did a surprising conclusion.
I had expected that Vista 64 would give a power boost, but this wasn't true. I had Windows 7 32bit installed. The editting went without delays. The system was able to monitor the recording without sound stuttering.
Weird was this problem is known due to slow harddrives. The harddrive cannot cope with the stream. On the desktop computer I don't have this problem due to faster harddrives, on the notebook I have. The weird part is that I was able to edit easier and faster on Windows 7 32bit than on the fast desktop pc.
I would have expected Vista 64 should perform the same or better than Windows 7 in 32bit… End conclusion is that Windows 7 is really faster with the same hardware even on 32 and 64 bit… On this 'old' notebook I have a preference for the 32 bit version because I can't upgrade to more than 4GB. Also some drivers and programs cannot deal well with 64 bit yet. But it is really well compared to Vista 64.