Do you archive emails from your Outlook? In that case, you might need to get the archive copies too, but as a general rule of thumb - yes - grab the pst file (usually outlook.pst or your windows-username.pst) and you are good.
If you really wanted to be on the safe side, you can do an export into a PST file from the Archive menu, just be sure to select ALL the folders, like calendar, contacts mail, notes and so on, because it will only back up the shit you select.
For future use, I recommend you move to a hosted exhange solution, they will do all your backups for you and handle any eventual shit which might come your way. Unlimited exchange storage, backup and push mail / Active Sync for mails, calendar and contacts to/from your phone for $9.95 per month. See more here:
http://www.myhostedsolution.com
Then if you ever lose your local copy, they have everything on their server for you. Also come with webmail, Outlook via Web access, very convinient when travelling without the laptop.