The ASUS offering is all very typical; it comes with a full version game, that CD wallet that gamers are so used to seeing and a three year warranty (while a lot of other companies only offer two). This does come at a cost, but to get yourself into an ASUS HD 3870 X2 you're still looking at under $600 AUD.
Where the GX2 does shine over the HD 3870 X2 is in a Quad GPU configuration. Tweaktown saw some good gains in Crysis when testing it, but the HD 3870 X2 in Crossfire really says nothing spectacular. With that said though, AMD are very good in the driver department and hopefully Crossfire X technology is something they choose to concentrate more and more on in the near future.