The core 2 Quad runs 4 actual threads and the i3 runs 2 with hyperthreading. The i3 also has graphics on the CPU. While I don't have personal experience with either of these as mine are different, I think you'd want to look at your personal needs. If you want to game, you want your own graphics card and not the i3. If you like to open multiple programs, you want more actual threads.
I'm looking to purchase one of these models and wonder if anyone can compare the performance of the SX2800-07 with the Intel Core 2 Quad Q8300 processor and 4GB RAM against the SX2840-01 with the Intel Core i3-530 processor and 6GB RAM.
Any comments would be appreciated.

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