Looks like you are a bit low in the graphics dept. Your total ram of 256 is low for todays applications..If your ram is fragmented you will get glitches in performance.If you have programmes that are running in the background as well ,that you are unaware of..these will also be chewing away at your available memory.!! .Shared graphics are a source of low performance and do have troublesome issues .For starters you could try one of the free memory optimizer programmes and see if that helps first.Go to ....
http://download.com
and search their range of utilities , or Google ..".memory optimizers "and you should get a choice ...As for updating your graphics card...do you know if you have an AGP slot on your motherboard ? Let us know a bit more about your P/C and we can help you better if we have a little more info..The update graphics card area covers a lot of ground and if you only have PCI slots , you will be limited in your choices..Post back a bit more info and someone here will be able to help you along .......Ed