Philip,
SQL express allows utilization of 1 GB or RAM, regardless of how much your server has, and there have been discussions in this post that discuss 8, 12,16,20 and 24 GBs of RAM in various scenarios. In these cases, assuming the server or main computer whichever your flavor, is going to be dedicated to AC, then the extra 7, 11, 15, 19 or 23 GBs of RAM is just taking up space. Upgrading to paid versions of SQL unlocks the RAM to do what it's supposed to do. Prior to upgrading the SQL server I timed out in certain applications in AC ~90% of attempts, now it's one-Mississippi, two Miss...and I'm on my way. And one more note... AC does not support anything other than SQL server 2005 express from what I understand, so once you've upgraded and there is an issue, the upgrade gets the blame from tech support, I speak from experience.
I hope my explanation of my situation help you with yours.
GNicoll[font:Microsoft Sans Serif] [/font]
