Users simply can't be expected to know what is and what is not a macro virus. Since I mainly use Word 5.1 when I use Word at all, I've never run into a Word macro virus and can't offer advice from personal experience. Of course, if you don't need Word 6.0's features, Word 5.1 doesn't suffer from macro viruses at all, and can safely open infected Word 6 files. Ideally, a future version of Microsoft Office would have a feature that would prevent macro viruses. In the end, be careful out there.
Vigilance is the only defense.
Only then can we hope to get the upper hand in the fight against the macro viruses.