Sounds likely. If you did indeed choose the option to use the entire disk it probably would have overwritten anything already there. Hope you didn't have anything important stored on the disk (you may be able to get some of it back using forensic techniques if you did, although I probably wouldn't recommend you try this yourself - get someone with experience to do it).
Originally Posted by Zorezz
Usually when attempting to dual boot with Linux you either need to resize existing partitions or use some spare space on the disk to do the install.
Anyway, to confirm, try posting back with the output from the following commands: