I am running Windows XP Home edition SP3 on 32-bit platform on my desktop. I bought the Windows 8 upgrade. Should I be trying for a 64-bit platform for greater speed, and if so, do I need to contact all my software suppliers to get the 64-bit versions?
If you install 64-bit Windows, the only software which has to be 64-bit is the device drivers for the internal computer components (sound, graphics etc) and drivers for any external devices like printers and scanners.
Because of this, you need to check your computer manufacturer's website to see if they've got Windows 8 64-bit drivers (or indeed any Windows 8 drivers at all) for your PC model.
The drivers they have will determine which versions of Windows you'll be able to install.
You really should have checked what drivers were available before buying the upgrade as you may have wasted your money (let's hope not).