Someone please help me

[Northbridge]

Which studies do you mean socket 775 against socket 939 or socket A against socket 478 ?

 

[Northbridge]

so will the AMD64 2800+ not be as fast as a 2.8c ghz ht?

If you can get a version of the 64 bit Windows XP when it comes out ( in beta phase now) the Athlon 64 2800+ will be a lot faster in a 64 bit OS compared to a 2.8C in a 32 bit OS.