The game has no control over how much video RAM is used. For Windows XP, the value is accurate, for the onboard video RAM being used, but it will not reflect any shared video memory being used from the primary system RAM.
You can experiment with the settings, but you will probably want to keep "Bump Mapping" disabled, along with setting the "Maximum Texture Size" to 1024, or less.
Some of the performance will also depend on the CPU and how loaded down it is.