Outlook 2007 includes another tool for shrinking the size of your .pst file by targeting your fattest folders. Select Tools --> Mailbox Cleanup and click the View Mailbox Size button. You'll see a screen like the one shown below.
There will be a list of folders, along with the total size of each folder. That will tell you where you'll be able to get the most reduction by cleaning out e-mails -- and their bloat-inducing attachments. After you find the largest folders, go back to the Outlook main screen and tackle those first, searching for unnecessary e-mails and attachments and deleting them.
After you've used all of these techniques for deleting attachments and e-mails, it's time to compact your .pst file. Normally, when you delete files and attachments, there are essentially blank spaces left in your .pst file that take up bytes.
Find your fattest folders.
Compacting the file eliminates those blank spaces and shrinks the total size of the file. To do so, select File --> Data File Management and double-click the Personal Folders entry. Then click Compact Now.
Annoyance No. 3
Why can't I find where my $#%^(@"* Outlook data is stored? All of your mail, contacts, attachments, calendar information and so on -- pretty much the whole Outlook data shebang -- is stored in a single .pst file. You often need to know where that file is located if you want to, for example, back it up or move it between machines. But Microsoft has a penchant for changing the .pst location from version to version of Outlook, and you might have a hard time finding it.
In addition to the .pst data file, Outlook uses a variety of other files that do things such as store your personal preferences. You often want to know their locations as well.
How to fix it: Outlook 2007 generally stores its .pst files in different locations depending on whether you're using XP or Vista. In Vista, you'll find it in C: \Users\YourName\AppData\Local\Microsoft\Outlook, where YourName is your Windows user name. In XP, it's usually in C: \Users\YourName\Local Settings\Application Data\Microsoft\Outlook.
Of course, there's also a chance that Outlook has stored them in a different location, but at least it's easy to find their location: In Outlook, choose File --> Data File Management. You'll see a screen like the one below. Look for the Personal Folders listing for your Outlook .pst file. Next to it, you'll see its location listed.
Finding your .pst file.
As for all the other Outlook files, in Vista, you'll find them in C:\Users\YourName\AppData\Roaming\Microsoft\Outlook, and in XP they're in C:\Users\YourName\Application Data\Microsoft\Outlook.