Go to crucial.com and input the machine specs.
Upgrading the speed, as in processor, is harder as you will probably need to replace the motherboard to match the new processor. With that goes new RAM.
Why would you want to buy a new machine with 64 bit? Lots of new machines out there with 32 bit.
I have a Dell computer with XP Home edition.It has Service Pack 2, Pentium 4 CPU 1.6 GHz 1.59GHz, 512 MB Ram. I wanted to purchase a new computer but will lose many of my programs that will be very expensive to replace, some that are no longer compatible with new 64 Bit machines. Can I upgrade The memory and speed of my computer? I would rather put the money in this machine and save my programs. Thanks smoker13