Q: ITunes - accessing info

What information do your want to access ? You can access and/or update your account's details via iTunes on a different computer (e.g. payment details, name and address, primary email address and password) or you can access/update some info via http://appleid.apple.com (name and address, email addresses, security questions, password).

If you mean redownloading your purchases, then what you can redownload depends upon what country that you are in - what you can redownload will show under the Purchased link under Quicklinks on the right-hand side of the iTunes store homepage on a computer's iTunes.

If you mean some other sort of info ... ?