Is Outlook opening correctly but not showing you your stuff or is it saying that it can't find the .pst file and asking for one?
Try going to the file menu and selecting open outlook data file, the requester should open in the default folder. On my system the file that holds my Outlook data is outlook.pst (there'll probably be another called archive.pst which should hold archived data).
The actual path the the file is long. You'll need to open your C: drive and step through "documents and settings" then the appropriate account folder followed by "Local Settings" (which is usually a hidden file so you'll need to be able to view these) then "Application Data", "Microsoft" and finally "Outlook".