I have some comments:
1. If you won't upgrade to second graphic card (SLI configuration), you don't need a SLI motherboard. You could get a nF4 Ultra motherboard and save some money for other components. Also check DFI (the best overclocking motherboard) or MSI brands.
2. Are you a gamer? If you aren't, that Creative doesn't worth
at all the money. I would choose an audio card based on VIA Envy 24 HT (M-Audio Revolution is a stunning card) - really better for music and movies than Creative. If you are a gamer... I still would think twice to buy that expensive card. Why? You won't get the chance to really use the superior power of X-Fi. Think about this: there are
few games today to support all the features of Audigy (EAX 2) on the market... And considering that X-Fi already has EAX 5... The create a game supporting all the features of X-Fi, a producer needs million of dollars for that because implementing EAX 5 in a game is a slow and painful job. Only big companies can afford the money. But this doesn't guarantee that many games supporting EAX 5 will appear in the following future. Don't listen to all "great" reviews of X-Fi cards...
I hope I made myself clear.