Does WinXP express install create expanding or plain hdd?

I want to free up hard drive space on my macbook pro. I noticed that my Windows XP hdd file is 31GB, but I'm using less than 10GB on that VM. I assumed that the VM is not expanding, so I loaded Parallels Image Tool, and when I get to the option to convert the hdd, there's a checkbox for converting to Plain, not Expanding.

I created the VM in May of 2007 and used the express install option. Does the express install create a plain hdd or expanding?

 

Back up VM, and check for Snapshots,
Be careful, reverting to old snapshot will erase files after that stage, you can copy necessary files from Vm, to external storage and merge snapshots

 

I had already removed any snapshots, because when I tried to compact the hdd, I got a message telling me to delete snapshots. I assume from your reply that the hdd should be expanding, but isn't.