Confused on selection of DVD for installation

Hi,

we are planning to install SAP on Windows 2003 and Oracle,when went to service market place to download the sofware DVD's we had confusion of downloading the correct software.

for example: "NW 7.0 SR3 Kernel 7.00 Windows Server on x64 64bit"

The X64 64bit menitoed above is for Hardware or the OS .i mean we have windows 2003 os of 32 bit and 64 bit and also processors of 32 bit and 64 bit.

Rgds,

rajesh