Should I reinstall Microsoft Word for Mac?

I have one of those pesky macro viruses for Microsoft Word 2004 -- Shankar's Virus. I've tried ClamXAV and a few other anti-virus programs, but nothing seems to work. Would it be worthwhile to uninstall Word? Could I reinstall it without buying it all over again for the confirmation code? If I could/should, how would I go about doing this?

Thanks so much!