video memory

hi. can anyone please give me as much information about video memory that you know. and how to upgrade it. also where inside of the computer can i find it to replace it. my system only has 2 mb of video memory and i really need to upgrade it i guess.

also as for ram? can u keep your old ram in your computer when u put in newer ram.

finally. whare is the model number of a computer found. i searched my system and can’t find it anywhere. would it be somewhere inside the computer. thecompany that made my system, “JPG SYSTEMS” has long gone out of business so i can’t phone them for help. anyone’s help will be, so much, appreciated. thank you.