Sometimes I need to locate large files to clean up a hard drive before it fills up and kills your system. This can be handy to use on a windows machine when you can't be bothered right clicking on each file and selecting properties to see the file sizes.
Download a live linux CD from one of the many vendors - my favourites are Knoppix and Ubuntu.
Load up linux from the CD - this will not overwrite your windows install.
On the desktop you will see all your windows partitions and drives, you will need to mount the partitions you want to search by double clicking them.
Now open a terminal and change to the mount point of your partition you want to search and run the following command:
find . -size +nM -print0 |xargs -0 ls -sSh
You will see a listing of all the files that are over the value n. Replace n with the size you want to search for - ie for 10MB type
find . -size +10M -print0 |xargs -0 ls -sSh
and this will find all files larger than 10MB.