transfering iphone data to another computer
Apple has an article called iPhone and iPod touch: About backups that has information about what and where iTunes stores things. These folders are portable and you can move them from mac to mac, PC to mac. I have had no issues when using different versions of iTunes - especially if the "receiving" computer is as new or newer than the "sending" computer. If you can update both before the transfer, that would probably be ideal.

iTunes places the backup files in the following places:


Mac: ~/Library/Application Support/MobileSync/Backup/
Windows XP: \Documents and Settings\(username)\Application Data\Apple Computer\MobileSync\Backup\
Windows Vista and Windows 7: \Users\(username)\AppData\Roaming\Apple Computer\MobileSync\Backup\


After the transfer completes, the backups should show up in iTunes and you can restore your phone form it. Do read the article iTunes: How to move your music to a new computer if you are not certain