I noticed a problem trying to install software with both sudo apt-get (etc.) and the software center, and after using
sudo dpkg --configure -a
I am returned dpkg: error: failed to write status database record about 'empathy-common' to '/var/lib/dpkg/status': No space left on device so I try
df -h

Be forewarned, I'm a complete Linux noob, so I'm sorry if this is a face-palm kind of question.
Thanks for the help!
EDIT1: 
EDIT2: Thanks for all you're help guys! It's been so long since I installed Ubuntu that I completely forgot I used Wubi. looking at it again, I can see that it defaults to giving Ubuntu only 17 GB. I can see now that I ignored that setting. I am currently reinstalling Ubuntu with a larger... group(?).