64 bit handles ram more effectively than 32 bit (i.e. u need to have more than 4gb)

Word of caution though before you install make sure that you can locate 64bit drivers (for your laptop) and 64 bit compatible software (depends on what software you use) especially if you are going to be running 3D applications.

If all the above parameters are certain then I'd say go with the 64 bit version

Edit: Atleast in terms of 64bit Windows Vista i have seen a marked difference in performance of 3D applications (3D Max and Maya) when compared to the 32 bit version (the configuration of the computers the OS was installed on being the same)

Which Windows 7 to install?
My laptop is 40% of my typical reading surface -- with the other 60% being a larger, desk-bound monitor.  Adobe Reader fails to use the entire size of the larger monitor -- cropping the PDF to about 2/3 the potential size.  Sumatra PDF Reader avoids this problem, but Sumatra doesn't let me cut and paste from my PDFs.  Is there a configuration or a PDF reader that lets me both a) fully enlarge the PDF to fill the larger screen and b) copy text found therein?

I'm using the nVidia graphics chipset in the laptop.
