Yes, for the psu.
More ram, dual video and SSD's would be personal choice's in my view.
Are you doing anything with your computer that would require more ram ?
A 22" monitor and a 5850 should suffice for pretty much any gaming, dual cards in my opinion would be pointless, unless you upgraded the monitor.
Haven't looked into SSD's yet, Raided WD Black's give me all the performance I need.