title says it really, I’m wondering which would be a better choice in terms of power and if it’s worth the added cost to get the 9800 GX2 over 2x 8800GT?
note: that’s 2 times 8800GT in SLI
It seems it depends on the game (see links below). I couldnt find an SLI 8800 GT perofrmance chart, but i would expect a 40 - 60% increase in performance when using SLI.
http://www.techspot.com/articles-info/92/bench/Crysis_02.png
http://www.techspot.com/articles-info/92/bench/Crysis_01.png
If your going for DX10 games I would choose the 9800, otherwise if DX9 games (and NOT thinking of the future) then I would get the 8800 GT SLI
right-o! thanks, I’ve made my choice 
9800gx2 is a better performer then 8800gt’s in sli, in older or newer games, sli with 8800gt’s scales fairly well, somewhere in the line of 70-85% but sli only really benifit gaming on higher re’s, 1920x1080 and up…so no, get the 9800gx2
thanks for the help in the end however, I opted for a single 9800 GTX 
A 9800GX2 is litrally 2x 8800GTS 512 (G92) in SLi but downclocked.