Recent review showed the 260 being neck to neck with the 4870; both in price and performance, those cards are in the same point.
Since my 8800GT should be between the 9600 and the 250, I guess that the best upgrade path is to buy a second 8800GT, reaching probably 260/4870 performance.
I searched the web for 8800GT SLI benckmark running in i7 920, but got no one single review...
I think that tomshardware should review non up-to-date cards as the 8800 and the ATI equivalents, in crossfilre/SLI, since for many users, it should make sense to buy a second card that to upgrade to a 260/4870.
older reviews on those cards does not accounted for the scalability on I7 x58 platform, and probably ATI and Nvidia dedicated more time tweaking drivers for newer cards, so maybe the 8800GT does not perform well today (the SLI on core 2/Quad did not worked very well in the past)