ive just upgraded my laptop to 4gb ram on 2x2gb pc2 4200 sodimm modules and in bios it shows the 4gb is there but when loaded up in vista shows only 3gb!!!!! where has the other 1GB gone?! can any help shed any light on this - kind regards chris

Hello and Welcome to PCHF

You will not see 4GB unless your using a 64bit OS.
When you have more than 3GB of ram the system reserves ram and hides it to prevent user programs from corrupting the system.

Read this article
TabBlogger : The 3GB-not-4GB RAM problem

thanks for the info -

Does that extra 1GB get used or is it actually wasted?! - if so i will out one 2GB module in my sisters laptop n purchase a 1GB Moudle if it wont make any difference...

would running XP make a difference?! sorry for all the questions but all help is very appreciated -

sorry thats supposed to read i will put one 2GB..........

ahh - the article - reading it now!!!!!!!!!!!!!!!