Which CPU and Motherboard?

Hi. First time on Toms and not 'too' hot with the latest tech so plz go easy on me.

Basically I'm going to build a pc from scratch for the first time as I believe it to be a great deal cheaper than buying 'ready made'. At the moment my old(ish) pc has a Gigabyte GA965P-S3 motherboard paired with an E6600 and stock intel cooler. The CPU has never been overclocked as I wouldn't know how to and wouldn't want to risk the damage.

The new PC will be used mainly for gaming (COD series, Fallout3, Crysis, Farcry2 and other FPS) with the odd bit of video encoding. It will also be based around a GTX 260 (216) which I would like to SLI at a later date. It also need to be, to a certain degree, future proof for a good 3-4 years.

The budget I've set for CPU and Motherboard is around the £270 mark but I may be flex up to £300 if needs be. Anything cheaper than £270 would be a bonus. After reading numerous forums, reviews etc etc I've come up with the following:

An Asus Crosshair 2 from Scan @ £122

http://www.scan.co.uk/Products/Asu [...] A-RAID-ATX

And a Phenom 2 x4 940 @ £140

http://www.lambda-tek.com/componen [...] ID=B176622

What would you do? Could I get better/similair performance with a different set-up? Could I save a few quid somewhere? Should I even consider a crossfire motherboard and ditch the GTX 260?

All comments/suggestions welcome.

Thx

In my old system theres 4 GB of Kingston DDR2 533 which I don't plan on moving to the new pc. I was going to ask about RAM in another thread as I'm not too sure about 'SLI Certified' RAM. Probably budget about £60-80, it all depends how much I can save with advice from you guys/gals.