Video properties - hardware acceleration - what does this do?

Under the properties section of the display, in the Settings tab, there is an advanced button. Clicking this brings up another screen which contains a troubleshooting tab. On this screen, there is a slider which allows you to change hardware acceleration from None to Full with a couple of stops in-between. Can anyone tell me what effects should I expect to see by changing this setting?

Reason for question:
Strange problem - I just built two systems, one with an 8800 GTS and another with an 8800 GT (both G92 versions). When using Quicken I get a very pronounced and annoying screen flicker. This does not happen when using an 8600 card. This problem is noted in several forums and the fix is to change the hardware acceleration. This fix does work but I am not sure what effects this could have on the performance of other programs.

Thanks in advance for any/all insights!!

Thank you for the reply nukemaster.

The flicker is only with Quicken, everything else works fine with no video problems. It seems to be a common problem with this software, there are multiple posts in the user forums. There were a couple of solutions posted concerning the mouse driver but this did not have an effect on my systems. The only way I could eliminate the flicker was using the hardware accelarator and moving it back two positions from Full. As usual, Intuit claims this is an Nvidia problem and Nvidia claims it is a Quicken issue.

I have to move the hardware accelerator back two positions to get rid of the flicker. This position references eliminating the 3D direct draw. Since Nvidia software has a screen (with many options) to control the 3D, I was hoping someone would know if changing any of these would help? or offer any other suggestions.

Again, thanks for the reply. I am not well versed in the graphics area and appreciate any/all help.