In regards to your question, how can you be so sure that your conspiracy theory about ATI and nVidia holds true? For all we know, the decision to go with only Shader Model 3.0 could've been a design decision that came from within UbiSoft. I wouldn't hold my breath waiting for some type of hard evidence that supports or denies this claim. However, that doesn't put it out of the realm of possibility. Also, the PC version of Double Agent has been said to be a port of the 360 version for all intents and purposes. This lends a little more credibility to the theory that the Shader Model 3.0 decision came at UbiSofts level (ie; they didn't want to or couldn't do SM 2.0 support) and was not influenced by ATI or nVidia.
x1300 and 6200's are not supported either. what does that mean ? it means cheap cards are not supported. nvidia and ati wanted to sell some hi-end gpu's. they knew that SC : DA fans would buy new cards just to play SC DA. i know few people who upgraded to 6600's...
if you consider going from an x850 to 6600 an upgrade of course.
It's not only that, if you have two cards in your system then the game will run slower than just having one. You have to dissable SLI in the control panel in order to use 1 card properly. If you use both cards it will work slower than a single card. FRAPS can be found at www.fraps.com
For now dissable SLI until Nvidia updates it's drivers or <b style="color:black;background-color:#a0ffff">UBI[/b] patches the game. Even if they do you can't guaruntee that Nvidia or <b style="color:black;background-color:#a0ffff">UBI[/b] will support it in the future. Frustrating I know.