Microsoft Windows 98, ME, 2000, XP and Vista users

Run the Disk Cleanup option

Open My Computer.
Right-click on the hard disk drive that you wish to regain hard disk drive space. For example, right-click on the C: drive.
Click Properties.
Within the General tab, click the "Disk Cleanup" button located next to the pie chart.
Windows will scan the computer for all files available to clean up.
Once in the Disk Cleanup window check each of the boxes (except "compress old files") that are taking disk space and click Ok and then Yes if you wish to proceed.
Compress?

When performing a Disk Cleanup you'll have an option to compress your hard drive. We strongly recommend users do not compress their hard disk drive and/or compress their old files.

Additional suggestion for Windows 2000 and Windows XP users:

Window 2000 and Windows XP keeps all the necessary files needed to uninstall any of the updates ever installed on your computer. Often this is several dozen updates that can take up several hundred and sometimes over 1 gig of space on your hard disk drive. See document CH000849 for additional information about these folders, how to locate them, and delete them.

Disable System Restore

Windows XP users can also decrease the default space utilized by Windows System Restore and often gain several additional gigabytes of hard disk drive space. See the below steps in customizing this feature.

Click Start, Programs, Accessories, System Tools, and open "System Restore".
Within the System Restore window, click "System Restore Settings".
Within the "System Restore" tab you can either check the "Turn off System Restore on all drives" to completely disable this feature, or click the Settings button and decrease the space usage, which we would recommend.

Disable hibernation

If you turn your computer off instead of using hibernation mode you can disable this feature to free up a lot of disk space.

Microsoft Windows 95 users

Users can regain computer hard disk space by performing any or all of the below steps.

Clean up temporary files

Click Start and then Search or Find
In the "File Type" text field type: *.tmp and verify the computer is looking at the C: drive or the drive that contains your operating system.
Search for files and delete each of the temporary files that are found.
Delete chk files

Perform the same steps as number one except search for *.chk and delete any of the files that are found.

Uninstall old programs or games no longer used

Information about how to uninstall programs can be found in document CH000347.

MS-DOS and Windows 3.x users

Users can regain computer hard disk drive space by performing any or all of the below steps.

From the MS-DOS prompt, type "del *.tmp /s" and "del *.chk /s". This command will delete any temporary files or scandisk error files on the hard disk drive.
Delete any software programs or games you are no longer using from MS-DOS or from Windows.