Solution a) Use the disk cleanup tool that comes with Windows
Solution b) Remove temporary files, as follows:
Click Start->Run, type "C:\Windows\Temp" (without quotes, where C:\Windows is the path to your Windows installation), then click Run
Click Start->Run, and type "%temp%" (without quotes), and click Run
All Windows versions:
Select all files in the folder that opens
Choose File->Delete (from the menu)
Confirm the deletion of all files. If any files are in use and cannot be deleted, deselect them (Control+click the file to do so), and so delete all the files that can be deleted.
Once all files have been deleted, try running the installation again.
See MS KB Question 230143
for more information.