Background: My father works at an office that doesn't allow connections to their Exchange server from the outside (no VPN, no RPC, nothing). He has his company email and a personal IMAP email (running off a server I manage) in Outlook 2007. For the past few months, he's had to wait for 40-50 minutes for Outlook to verify his (apparently) 'damaged' PST/OST file(s) (unsure which ones it's testing) every time he starts his computer (this does not happen if Outlook is opened and closed; maybe because something running in the background).
Data:
He's running on Windows Vista with an up-to-date Outlook 2007 install. His C:\Users\[Account]\AppData\Local\Microsoft\Outlook folder looks like this:

I think the issue is probably with the 19GB OST file; I don't know Exchange, but it would make sense that the mail cache shouldn't get that big (there is nowhere close to that much mail in his mailbox; maybe 1GB at most).
I'm debating just purchasing Office 2010, making the administrator at his office forward his Exchange email to an address I control, and starting him over from scratch (as an aside, does Outlook 2010 have a "unified inbox" like Mail.app on the Mac?). I may just do that.
For now, is there any way to prevent Outlook from scanning these files upon startup, or is there any way of compacting the files?