Hello johndoe777,
Your contacts (as well as your email, to do, notes, etc) in Outlook are contained in the Outlook database files that end in .pst. These files are stored within your user account's profile folders and are normally not affected by installing or uninstalling Outlook and/or Office.
But there is much more about Oulook than the data in the .pst files. This link
http://www.backup4all.com/kb/backup-outlook-emails-and-settings-125.html has a very useful list of all of the files that need to be backed up to properly backup an Outlook installation.
Your question leads me to believe that you do not regularly backup your Outlook, and may not have any sort of regular backup in place.
This would be the perfect time to correct that problem. You did not mention which Windows you are using, but the Backup in Vista and Win7 are vastly improved over XP, and even XP's clunky backup is better than no backup.
Please have a look at this web page to determine if you meet the requirements for the Office 2010 Technology Guarantee:
http://office2010.microsoft.com/en-us/tech-guarantee/microsoft-office-2010-technology-guarantee-FX101825695.aspx?redir=0
For great advice on all topics XP, visit http://www.annoyances.org/exec/forum/winxp
