Foss is Free and Open Source Software. Here is an example of it's usefulness:
The computer had 2 hard drives, one 20 gb (C: drive) and one 150 gb (D: drive). Windows is complaining about running out of space on the C drive. What to do? Well - first back up everything - don't make that mistake!
Next, using Gparted Live CD (FOSS) we reformat the D: drive. Then switch to Clonezilla (also FOSS) and clone the C: drive to the D: drive and back into Gparted Live. We resize the cloned drive to the full capacity of the 150 gb drive and change the flags to make the computer boot from the D: (betcha can't do THAT with Windoze!). Back into Windows - restore the backup of the D: drive to C: and rename them. Now we have a 150 gb C drive and plenty of room for storage on D:!
