Sure? 700mb of shared memory is not something I have encountered. The shared memory option is set in the BIOS these days, but the most I have ever seen is 128 never this high a value.
Is your graphics card onboard, or is it a seperate card? To check the shared memory settings enter your BIOS screen on boot up (usually by pressing the DEL key while the machine boots. Take care not to make any changes not related to the shared memory option or your machine may fail to boot.