With planning it should be possible to keep your users running when the Office System Beta 2 Technical Refresh expires this weekend. Fortunately, you have until May 15 to upgrade your SharePoint servers.
What are your options? Get the appropriate licences and upgrade Office, or delay the decision another 60 days by upgrading to one of the Office System trial versions.
To learn how to upgrade your servers read the section called "Beta 2 TR Upgrade Resources" in Joel O's post on upgrading to RTM.