I found this trick yesterday for freeing up disk space on tight Windows 7 installs by using an automated tool to purge the C:\Windows\Installer directory. Windows 7 users with monster HDDs won’t have to worry about this, but if you’re running Windows 7 on a small SSD, you will.
But what if everything in C:\Windows\Installer is in use, like it was on my machine? Compress it!
You can right-click in Explorer and select Compress, but there’s a faster way.
Open an administrator command prompt, then issue the following command:
compact /c /s c:\windows\installer
Then it will buzz through the contents of the directory, telling you how much space it saved on each file, and in the end, you get a grand total. I was able to save 200 megabytes. Not a lot, but not chump change, either.
While you’re at it, there are some other directories you can give the same treatment:
The return on investment there is more likely to be along the lines of tens of megabytes, but again, it costs no money and a minimal amount of your time. You can switch to another task and check back in a few minutes to see what you saved.
The more space you can free up on a small SSD, the better the wear leveling will work and the longer the drive will last. Although I haven’t actually tried this myself, the theoretical life expectancy of an SSD running at 90% capacity is around 3 years.