Nforce 570SLI vs AMD 480X CrossFire

Hi im about to buy a new motherboard to pair up to a X1950GT and was wondering whether the:

Asrock ALiveXFire-eSATA2 (Socket AM2) PCI-Express DDR2 Motherboard
http://www.overclockers.co.uk/showproduct.php?prodid=MB...

OR The

Foxconn N570SM2AA-8EKRS2H NF570 SLI,
http://www.scan.co.uk/Products/ProductInfo.asp?WebProdu...

The reason I ask this is because i am wondering whether the DX10 cards will be better in SLI mode than Crossfire mode.

Just tell me i am wrong if i am, but i thought i read about this somewhere.

Any help much appreciated.