Uninstalling Spybot S & D

I wish to uninstall Spybot S & D so that I can download a newer version.

My current version will not install updates and gives the message: “Bad checksum” for each update.

In Add/Remove Programs I am advised that if I uninstall S & D all the backed-up files will also be deleted.

What should I do?

I also have Ad-Aware and Xoftspy installed.