Backing up Outlook PST file to CD/DVD

Windows XP SP3 - I have a client that wants me to back up his Outlook email account (the PST file) to a CD/DVD. Normally, this is not a big deal, but he has 4 different PST files on the PC. Three of these PST files are in Documents and Settings\%username%\Local Settings\Application Data\Microsoft\Outlook and the names of these files are archive.pst and user@blablabla.org.pst and Outlook.pst. The Outlook.pst is the largest so I'm assuming it's the most complete and current file, but there's also another Outlook.pst file in Documents and Settings\%username%\My Documents\Downloads which I thought was weird. It's 282mb in size compared to over 2.5gb for the other "Outlook.pst" file. SO I guess I'm wondering which file to back up? All of 'em?

Thanks!

 

Never mind . . . . I just saved all of the files . . . .

 

Just F.Y.I. if you open the Mail applet in Control Panel, Outlook Data Files, you will see what files are actually used by Outlook.

PST files with a size of 265KB are empty files.