Ok that the Autorun.inf-file is unsafe. So you can turn it off manually or there are hundreds of tools available for automating this. But turning it off is uncomfortable for most people. Here is an interesting, open source program; USB Cop (alpha) that will protects you by blocking autorun.inf file when inserting a USB device.
What the program does is that it warns about autorun.inf files when you inserting a removable disk so that they won't harm the other PC without autorun turned off and will display the content of the autorun.inf file (if any) and allows you to browse the files. You can also delete these files.
The software (still in Alfa stage) is clean and supports Windows XP and 2003.