At [H]ard|OCP, they compare the new HD 2900XT to the 320MB version of the 8800GTS and use it to exemplify the disappointment many people felt with the release of the new card from AMD.  Although both cards performance falls mostly within the same speed, a certain card does pull ahead noticeably in some of the benchmarked games.  Unfortunately, it is not the $400ish AMD card that pulls ahead, but rather the $250ish nVIDIA card.
“See how the 320 MB version of the GeForce 8800 GTS compares in games against the ATI Radeon HD 2900 XT. If video card value is what you seek, you will want to read this. We have also included some Lost Planet demo DX9 testing with interesting results.”

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