XP supports ZIP archives without any extra utility. Apparently however, ZIP files that were previously password protected no longer need the password to extract and view the file contents. Therefore, be careful if you rely on password protection on ZIP files.

Oops! I spoke too soon @#$%&*!

The ZIP file that I thought was password protected apparently was not. I performed a test by creating a new one with a password, and XP does indeed ask for the password, and will not display the file contents without it.

Be careful anyway, because I could have sworn that other file was password protected all through my Windows 98 career...