You say you have asked for 7GB AWE memory on a 8GB box. Do you have the message at SQL startup that says you have allocated this memory? If not, then SQL is using probably only 1.6GB memory which could be less than it had before the upgrade.

You are very unlikely to get much more than 6GB memory allocated to SQL Server on a 8GB box. Depending on what else is running, even 6GB may be hard to achieve.

If you have time to experiment, try reducing your memory setting by 0.1GB steps until you get the startup message that AWE is being used, then reduce memory by another 0.1GB to give a safety margin. You should periodically review the startup messages, especially if SQL is a lot slower after a restart, as all sorts of Windows, anti-virus, SQL, etc fixes will tend to use more memory than was needed without the fixes.