Your beach ball effect is most likely being caused by your onboard graphics struggling with the dual monitor setup, flash game etc.
Remember the on-board steals some memory too. You could also argue if you have a 5400rpm HD, that it's taking a beat to keep up with you.
4GB is plenty of memory for over 90% of users. The next logical upgrade, way before sticking 8GB of memory, is an SSD drive.
Still, enjoy your purchase, that will be a truly awesome machine, though don't be surprised to see the beach ball again. Those things always crop up.