<< i hate it when ppl do this
how much would it have cost ya for a few friendly lines to answer the question? >>
How much would it have cost you to check the FAQs or perform a search?
Sorry about the tone.
I have had to answer the same question many, many, many times.
All it takes is for someone to take a quick look through the FAQs. I and several others have spent a great deal of effort writing all of these articles, in order to answer your questions in the best possible manner.
I think it is a poor repayment to the writers of the FAQs that people never bother to read them.
As for Windows XP, it falls under the same category as Windows 2000: the maximum addressable and useable RAM is 4GB.