As long as you go into iTunes first and uncheck any of the "Sync" features and the backup option.
The way iTunes works is to sync the iPhone based on the Computer, so be default it will take the information from the computer and try to put all the music, contacts and data onto the iPhone.
Your best bet would be to setup a new userid on your computer and the make sure that iTunes is not set to allow any action but the prompt for "Update".
Dave