If you have time and diskettes, do a full backup of the program directories as well. In the normal operation of a hard disk, platters of magnetic material are spinning and read-write heads are kept barely above the surface by air flow. When the hard drive is turned off, the air flow ceases, and most hard disks will simply let the read-write heads settle onto the platter on the area last read. If the hard disk is jostled, the read-write heads can make that part of the disk unreadable. In the worst case, the heads can scratch the surface of the platters, creating loose particles which can cause further damage when the drive is used later.
Some computers have a ship command, which works exactly like the park hard disk option.
Read your user manual or call the technical support line of the vendor for details. There may be a Reference Diskette that was supplied with your computer. Select that option and follow the prompts. The next time you turn on the PC, you can use the hard disk again as if it had never been parked. If the system unit is bolted to a table, check with the moving company about moving both as a unit.