It's still an advantage over the 512MB version which I stated, and even 2100 memory with 256bit bus does not match the bandwidth of the GTX or Ultra so thats also still an advantage, nothing you said changes this.
Also, this is about selling the 8800GTX for a 8800GT, not which is faster as we all should know the answer to that, 8800GTS is still an unknown as we don't know for sure which core it's using or where it will be priced.
True but your question was "should I sell my GTX?" and be whether you replace it with a GT, the new GTS has a bearing on that answer.
SHort term, no it's not worth selling your GTX for a GT.
In a few weeks when leaked (hopefully) results come in on the G92 GTS 128 SP, then it might be a different answer cause if the new GTS does beat a GTX and the price is £200-£250 range then 2nd hand prices of GTX cards are going to drop just like 8800GTS cards have now.
So I would keep your GTX for now but look again at maybe selling in a few weeks time



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