1- This G.Skill Ripjaws 4GB (2x2GB) 1333
are very good and are a very good option for u.
2- The PSU is overkill for your rig, this are the power requirements for your GPU. ATI Radeon™ HD 5850 System Requirements
* PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard
* 500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended (600 Watt and four 6-pin connectors for ATI CrossFireX™ technology in dual mode)
* Certified power supplies are recommended. Refer to http://ati.amd.com/certifiedPSU for a list of Certified products
* Minimum 1GB of system memory
* Installation software requires CD-ROM drive
* DVD playback requires DVD drive
* Blu-ray™ playback requires Blu-ray drive
* For an ATI CrossFireX™ system, a second ATI Radeon™ HD 5850 graphics card, an ATI CrossFireX Ready motherboard and one ATI CrossFireX Bridge Interconnect cable per graphics card (included) are required
The recomended PSU is for the entire system, with this Antec 650W
is enough for your rig and the future Crossfire and CPU upgrade that u want.
3- IMO the mobo is very good, but if u want OC the rig, u can wait two weeks for the Gigabyte 890FXA-UD5 that is a better mobo for OC.