The numbers clearly speak for themselves: The 7800 GTX in SLI is a must have for any serious gamer. From conversations we have had with system builders, we found out that they are paying up to $200 over MSRP for them, so be prepared to drop a cool $1,600 if you want a set for your SLI rig.
As for a single card solution, NVIDIA did it again. The card is impressive by itself or with another one in SLI. If you were looking to get that duplicate 6600 GT, you might want to reconsider your purchase. It might be worth it to pick up a single 7800 GTX instead of getting the other GT.
However, if you are looking at this review scratching your head because you just bought a 6800 Ultra, you might have a bit of a dilemma. Your wallet might want another 6800 Ultra after the price drop takes effect, but your pride will tell you that you would be better off forgoing the SLI and getting the new card. Either way, though, you are sure to be the envy of your friends - which is what your pride was after in the first place.
If you are reading this review and laughing at the people who spend money like water on bleeding edge technology, this card is not for you. The Intel IGP is in the next aisle... it will do you just fine.