You will need a 64 bit processor for 64 bit Windows, Yes, you will need to replace the processor, but also need the 64 bit drivers for the rest of the hardware. There is a compatibility test available @ microsoft.com.
The information on Computing.Net is the opinions of its users. Such
opinions may not be accurate and they are to be used at your own risk.
Computing.Net cannot verify the validity of the statements made on this
site. Computing.Net and Compnet Ventures, LLC hereby disclaim all responsibility
and liability for the content of Computing.Net and its accuracy.