New build for Aussie gamer

Im basically looking at upgrading my AMDx2 system to an Intel quad over the next couple of months. Havnt used intel for a long time wouldve prefered to stay with AMD so im guessing id be best of with a i7 quad. Will be mainly using it for Gaming (mainly fps) and surfing the net. Quite often have alot of apps running at the same time extracting, encoding, watching a movie all at the same timer. I have a lot of stored data and a raid backup setup for the most important stuff may be worthwhile for me.

APPROXIMATE PURCHASE DATE: in the next 2 months will buy parts over time

BUDGET RANGE: $400 - 600 mobo $300 ram $400-600Cpu

SYSTEM USAGE FROM MOST TO LEAST IMPORTANT: Gaming, surfing the internet, watching movies, minor video encoding

PARTS NOT REQUIRED: OS, GRAPHICS CARD have 2x gtx285 2gb ,Case

PREFERRED WEBSITE(S) FOR PARTS: whatever has the best price

OVERCLOCKING: Yes Maybe SLI Yes

ADDITIONAL COMMENTS: Will buy http://www.pccasegear.com/index.php?main_page=product_i...

Already have 2x GTX285 2GB , 4x 1tb hardrives, monitor, mouse

Ive had a look for motherboards and come up with these three
Gigabyte GA-EX58-EXTREME
http://www.pccasegear.com/index.php?main_page=product_i...

EVGA X58 Classified E760
http://www.pccasegear.com/index.php?main_page=product_i...

ASUS Rampage II Extreme
http://www.pccasegear.com/index.php?main_page=product_i...

Im leaning toward the Gigabyte as ive used there boards for the last 2 builds ive done.


Also looking at getting this for audio/video playback
ASUS Xonar HDAV1.3 Deluxe
http://www.pccasegear.com/index.php?main_page=product_i...

Not sure what the best ram and Cpu would be as i generally wouldn't even think about building an Intel system so any help or suggestions would be appreciated.

Thanks