it does let you, but it is recommended to have 15%.
Because it uses that 15% to move files around. If you have less than 15%, it wont fully defragment.
they make you sign up to play an online game on the loving internet what the forget (bf: bad company, xbox)
Yeah, I start up The Godfather 2 on my Xbox. Bam, EA signup screen. I'm like "What the forget? Is my Live account not good enough?"