You will probably find , your laptop as onboard graphics card which will use the ram from your system , your friends tower pc will have a seperate graphics card that as its own ram source.
The graphics on your laptop system is probably more than adequate but would probably improve with an upgrade of ram, you can try this link SYSTEM SCANNER and download and use the scanner to see if its possible to increase or improve your system ram ;-) ......this would be the cheapest option.
Hope it helps
edit: as an after thought, if your using windows Vista or Windows 7, have you tried using a memory stick with READY BOOST , might be worth a try to see if it improves for you ;-)