Go to microcenter. They have the lowest price on processors. As for MOBO, ask them to price match neweggs price on MOBOS.
Corei7 920 $200 at microcenter. Core i7 930 $230 at microcenter. If you don't plan on overclocking, then go with Core i7 930.
I like the MSI X58 Pro-E, it will support all your needs from SLI to raid. (7 Sata, 1 PATA, Raid 0/1/5/10, SLI. It is only 189.99 at new egg with free shipping. Microcenter will match that price.
As for memory, I'd go for OCZ or Corsair. Which ever is cheaper. Since you are doing alot of video transcoding I wouldn't go anything less than 6GB of DDR3. There is nothing that AMD puts out that can compete with the Core i7 processors.