Outlook 2003: In Outlook, when I right-click PERSONAL FOLDER
(then) FOLDER SIZE, the Total Size shown (incl. subfolders)
reads: 541,364 KB.

But when I go to C:\Documents and Settings\(User Name)\Local
Settings\Application Data\Microsoft\Outlook\Personal Folder.pst
the size (in detail view) is shown as: 1,310,409,728 (1,279,697
KB).

How can that be?

Not all programs are very accurate and may have not included files it doesn't recongnize or just didn't include files just becuase it didn't. I would trust Windows (assuming you have it from your file location) more than Outlook....even though it's made by the same company .

the .PST file for Outlook contains several kinds of data:

Contacts
Apointments
Task lists
Notes
and Email

The size reported by the Explorer for the ..\Outlook\Personal Folder.pst is the RAW
file size for ALL of the content managed by Outlook.

The size reported by Outlook for a specific folder is a subset of the single *.pst
file.

Thanks Guys! But I have a question. Jobeard: I understand your distinction between Raw and Specific data, but when I'm in Outlook and select the ultimate parent folder, <Personal Folder.pst> by default, doesn't that include all the subfolders, including those you mention? Isn't that identical to including all the Raw data? The thing is, I've never seen this discrepancy before.

As I have Outlook 2000, my layout is different and I can't see the same thing
in the Oulook GUI left hand presentation ... this is about as far as I can take you ...
sorry

edit:
when did you last empty the Outlook trash or compress the folders?

Outlook 2003 starting to use XML format as prior 2000, 2002(XP) didn't use. You can always compact the files or move PST to different locations. This way should anything happen to your HDD you can alway have a backup on a different PC or use backup software daily. I use here as just like you would setup and Exchange Server keeping the PST in an Exchange folder off on another PC on the network. Each PC running Office 2003 and if it has Outlook 2003 can access these PST and PAB. If I run the full blow Exchange Server in SBS then it would be more idea.