SharePoint Quota Gotcha
Let's say you've created a SharePoint site and assigned a quota of 3GB, "just in case they need it". Now let's say the site currently contains 788MB worth of files.
Q: How much disk space does it consume in the database?
A: 3GB. Try exporting it using STSADM and you'll find that the backup file is approximately 3GB.
This is something you should be aware of when setting quotas.