OS X mavericks will not install GUID partition

At one time I had Parallels installed on this drive.

Now when I attempt to install Mavericks I get "This disk doesn't use GUID Partition Table scheme.

It tells me to go to disk utitlity and repartition with GUID.

If I do that I lose all my programs and data.

Any other ways to install Mav and not have to do a repartition?

Cliff