First of all updating your RAM would be good. You also need to get more system resource freed up. close all your windows and see how much resource you have. If its still 42% then you are running too many task bar things. Every icon that sits in your taskbar (by your clock) uses computer resources and makes the computer work harder. You have a start/programs button that has all of your programs there with easy access delete the ones in your taskbar that you dont need there. To do that do the following:
BE CAREFUL WAHT YOU UNCHECK!
(You can always go back and recheck anything you uncheck, but make sure its stuff you know are related to programs you dont need running at startup. You will see things you ahve no idea what thye are for.. leave em checked if your unsure)
Click Start - Run - type in MSCONFIG
A screen will pop up.
along the top of that screen are tabs.. click on the STARTUP TAB. Click to full screen so you can see the paths and what each name is related to.
Uncheck everything that you dont need running at startup.
It will ask you to reboot.. do it.
If you are running Windows ME, you will be told at startup that you are using selective *something or other, I cant remember exactly) check the box for ok. This is just something telling you that you unchecked some options..no big deal)
See how much resources you have. You should have at least 70% free when not running any programs.