I have just installed and run the latest version of Blender, 2.64a; BUT: The Blender UI has a response time which is unacceptable ! I guess this is due to my graphics card, a NVidia GeForce 6200 ? My OS is Win XP Pro.

What is the recommendation for running Blender 2.64a on Win XP Pro smoothly ?
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In heaven there's no beer, that's why we drink it here ...

Of course, i have no idea how much you are trying to display in your viewer. But my GUI response times are fine, even on a GeForce MX4000.
(2.4Ghz, Pentium 4, XPPro)

The 6200 should be fine. Are you sure you are running the latest drivers?
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Spacemice / Blender Compatibility

Thank You very much for Your encouraging answer, Tehrasha ! It has motivated me to do the following:
- Install Blender in another, more barebone Win XP Pro partition: It ran smoothly immediately !
- Reinstall Blender and reboot the troublesome Win XP Pro partition: It runs smoothly, too ! With smoothly running I just mean starting Blender and doing some clicks in the UI; I have not done any display hardcore tests until now.

Recently I have already installed the latest driver for the GeForce 6200 card; therefore, the hope is now that my Blender exploration can go on.
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In heaven there's no beer, that's why we drink it here ...

Some general hints:

Use the video driver from your card's manufacturer.

Turn off eye-candy like compositing, transparency effects, and themes like Aero or compiz