My name is Krishna and I work for the Social Media and Community Team at Dell. There are a couple of free programs that make it easier to see how space is allocated on a disk. SequoiaView and WinDirStat can both be downloaded from Snapfiles.com and they will give you a graphic representation of your files. You can also try running Disk Cleanup and deleting restore points and shadow copies (assuming you don't need them).
However, It is important for you to create recovery disks before you delete any files. It's definitely a good idea to have them since the recovery partition will be history if the hard drive fails. For Instructions to create your systems recovery disks, go to http://dell.to/o1Kh2A . Hope this helps!