<p>Wikipedia says SQL Server Express Edition is limited to "one processor, 1 GB memory and 4 GB database files".  Does anyone have practical experience with how well this scales?</p>

We have used SQL Server Express Edition in some of our smaller applications, maybe 5+ users, and smaller databases.  The 4GB is very limiting in a high transaction environments, and in some cases we have had to migrate our customer to SQL Server Standard Edition.