Temporary files are just that: "temporary". These are files created by programs you are using. Generally, when you close a program, the temporary files are automatically deleted. But, alas, sometimes they are not.
In Windows 98 / ME / 2000 / XP, Microsoft provides a 'Disk Cleanup' utility which will automatically locate and delete these temporary files.
1. I always suggest to first restart your computer (just to be sure). So go ahead and click Start -> Shutdown -> Restart
2. After your system is back up, double click on 'My Computer'
3. Right click on your C: drive icon
4. Then click on 'Properties', and the following window appears:
5. Click on the 'Disk Cleanup' button and the following window will appear:
6. Click OK and in a few seconds you will have deleted any temporary files that have been accumulating. I suggest doing this at least weekly!