Well I have 2 suggestions.
the first is to use our recommend file cleaning utility, ATF (see below)
The next would be to use Windows disk visualizer: WinDirStat
The free, open-source utility WinDirStat displays your disk usage in a color-coded map that shows what file types and folders take up the most space on your hard drive.
More info on this can be found hereUsing ATF Cleaner on Windows
If you haven't already downloaded ATF Cleaner, you can download it from HERE
Once you have it downloaded, run it and you will see a window similar to the following:
(Please note that only on XP and Vista machines with it enabled will the Prefetch option not be grayed out
Now click on the Select All
checkbox so that every checkbox listed is filled in with a checkmark.
(You can uncheck any of the items you don't want to have cleaned
Now click the Empty Selected
button. It will take less then a minute and you will receive a window stating that the cleaning is done and how much space was freed up.
That's all there is to it!