Will you be overclocking? If you will be overclocking, will it be mild? You could save some money on a few components.
And scrap the 790i, you're paying way too much for a chipset made by Nvidia. Go with a P45 board, like the ASUS P5Q PRO. The SLi upgrade path isn't worth it since 4-way SLi scales like crap (often backwards).
RAM: Team Xtreem DDR3 4gb PC-16000/2000
Scrap the DDR3, the Q9550 runs a 333MHz FSB (1333MHz quad pumped), that's DDR 667, the higher speeds of DDR3 won't be of any benefit to you because of the FSB bottleneck.
Also, no wireless mice
For the PSU, unless you're doing some serious overclocking, a decent 500W-600W unit with a 6 pin and an 8 pin PCI-E connector should be more than sufficient: This if you don't overclock. This if you do.