my board of choice
I use the 940 BE with it and run a full time 265x14 = 3.7 Ghz with 8 gig DDR 2 1066 @ 1056 overclock.
Amazing speed and power.
Don't think I would recommend a DDR 3 setup yet. Cost is far to high and there is utterly no benefit in doing so.
When you pick graphics
Give me your budget for GPU so I can recommend a good one for ya.
Memory
what I use and just rocks I use 2 sets of them for 8 gig total.
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AMD phenom II 1090T @ 4.23 Ghz custom water cooled
Asrock 890 FX deluxe 3 mother board
4 GB DDR 3 1600 @ 1688 Mhz 7 7 7 24 T1 2688 Mhz NB
2x 1 TB WD Sata III 64 mb cache HDD,s raid 0
2x 5870 HD @ 1015/1300 Asus reference
Dual OS win 7 x64 ultimate & win 7 x32 Ultimate (bench os)