2. Turn off unneeded Desktop Features that try to make things look better. The fancy rounded window corners, the way the menus fade in and out, and the 3-D button styles on modern Desktops all require some computing power and can overwhelm older machines. To turn off these appearance only enhancements:
Windows XP - right click on My Computer, and choose the Properties option, then choose the Advanced tab, and click the Settings button under the Performance section. In the Performance Options dialogue that comes up, go to the Visual Effects tab, and choose "Adjust for best performance". You can also try the "Custom" option, and turn on and off individual settings to see which ones will work without slowing your machine down.
Vista - Click the Start button, then Control Panel, then choose System and Maintenance, then Performance Information and Tools. Click Adjust visual effects. If you are prompted for an administrator password or confirmation, type the password or provide confirmation. Click the Visual Effects tab, and choose "Adjust for best performance". You can also try the "Custom" option, and turn on and off individual settings to see which ones will work without slowing your machine down.
Windows 7 - Click the Start button, then Control Panel, and then System and Security. When you see System, click on it and then Advanced system settings. From here you can make sure you're on the Advanced tab and click on Settings under Performance. Here, you can also choose Adjust for best performance or choose Custom if you'd like to compromise between fancy visuals and performance. On a side note, this menu can be accessed much quicker by right-clicking on Computer, from either the Desktop or Start menu, selecting Properties, and then Advanced system settings.
Follow here for tip 3-
http://answers.techzim.co.zw/11281/is-your-computer-slow-tips-to-speeding-it-up-3-13
