With the money saved on RAM, you could upgrade to a 5850, though I suspect that both the 5850 and the 5830 are overkill for your current resolution. The 5850 would be a better long-term investment if you end up buying a 1920x1080 monitor.
The PSU is overkill for what you have or could ever put on that motherboard.
I would consider dropping to a Corsair 650TX for $90 ($70 after $20 MIR), and either simply save the money, or try to upgrade your monitor.
You can get 1600x900 20" monitors for around $130, and 1920x1080 21.5" monitors for around $160.
In theory, you could go with a much lesser AMD chip like the Athlon II X3 and not see much reduced performance in gaming.
Putting a 5830 to run a 1366x768 monitor is like putting a 350 small block chevy on a lawn tractor. It don't make no damn sense.
SO....What work do you do that you need 8 GBs of ram? Unless you're doing heavy professional grade graphics/vid/pic editing, you'll never use all of the first 4 gbs9, let alone the second 4. I'd say drop the second set, and then use the money for a 1920x1080 or better monitor.
You can also save some money by getting a smaller PSU. Even with the extra fans and leaving room for second 5830, a 650w will do just fine. You could find something modular to help with airflow, that 850tx will have a whole lot of cables you'll never use and have to tuck away.