Removing the wallpaper can help increase start up times, and help programs load faster, especially on older PCs. To do this, right click on your desktop, go to properties, go to wallpaper, and click on none, then click apply.
Step 2: Change the Theme
Simply changing the way windows looks can drastically increase you computers speed, try changing from Windows XP to Windows Classic. Right click on your desktop, go to properties, go to themes, go to windows classic, click apply.
Step 3: Exit Background Programs
Turning off the programs running in the background of your computer can hugely increase you computer speed. Right click on any program in the task bar you don't want running, and go to exit. Careful no to exit anything important though.
Step 4: Download a RAM Program
There are many programs available that allow you to free up RAM on your computer, you can get a lot of good, free ones at c net's download.com.