There are posts for this in the help section, under the FAQ's.
However, the simple step would be to copy your existing data & model files (VGHDData & VGHDModels)to another machine or external hard drive and then coopy them back before your reinstall the VGHD Software.
A good idea might be to install a secon hard disk in your PC and copy and leave the files there.
Then after you rebuild your PC, you could point the VG softeware to the new data location.
PS:
A better place for this post would have been in the problems, Bugs & Fixes category.