How can I be sure my VHS is not going to erase while I record it to DVD?

I need to copy the VHS of my wedding tape to DVD-R on a TV/VHS/DVD combination. I am terrified that my VHS tape will erase while it's recording onto the DVD, and if for some reason the recording doesn't work, I will no longer have my wedding tape! My VHS tape has the black square hole removed on the back. Does that mean the VHS tape CANNOT be erased? HELP!

Beth Wood
July 2010