While HDs are relatively cheap these days, you might be able to pick up a used complete system for about the same cost as a new HD. Check the classified adds in your local paper. Better yet, if there's a freeby classifieds-only rag in your area, chech that too. I've seen adds for PIII, 600MHz systems -- cpu box, monitor, KB and mouse, loaded with Win 2K or later -- for as little as $50, while later systems (PIV, >1GHz) go for as little as $350 complete with a printer.
At those prices it's hardly worth the effort to resurrect a "boat anchor".