Virus and spyware definition files are updated daily usually, so the best you could hope for is a snapshot of when you made the disc.
To make matters worse, while there are still some command line virus scanners, I don't know of any spyware removal programs that will run without Windows, and there's no way to make a LiveCD with Windows like you can Linux. You can't even simply run the programs off of the CD (floppies wouldn't hold nearly enough data) because Windows needs files to be installed on the hard drive.
It's a good idea in theory, what you want to do, but it's not really possible with Windows.
How is the best way to create a bootable disc, with antivirus and antispware progras I can run without installing any programs on the PC itself?