I would say the 4890 is your best option although the GTX 260 is also not a bad option.
The 4890 is at least as fast as the GTX 275, costs less and has great overclocking margins.
While the GTX 260 is the slowest of your options, it is also the cheapest.
Depending on your resolution, it may be more than enough.
------------------------------If the automobile had followed the same development cycle as the computer, a Rolls-Royce today would cost $100, get a million miles to the gallon, and explode once a year, killing everyone inside.
PSA
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