The accelaration function of your graphics card uses hardware to speed up the processing of graphics by handling some of the work itself instead of yer PC.
Unless you use software that requires accelaration (normally 3D effects and mostly in games, although some high-end graphics packages use it as well) you won't notice any difference.
If you were a sad old bugger like me, and bought some of the recent Star Wars games, you will find that they just will not run without the accelaration on. Most of the flightsims can use 3D accelaration, but it's usually off by default.
To be honest, my dear chap, your card is quite simply junk and should be replaced with a decent one asap
Try any Voodoo card or something from the Matrox range - they tend to work with everything !