Acrobat's likely to already be installed with their Web browser, which you can check by sending them a URL to a PDF and see if they're able to read it. In that case nothing to install, and you get the best of both worlds: Simplicity of sending them to a URL, simpler for you to create PDFs than Web pages (Word produces really horrible HTML, BTW).

I'm pretty sure that the latest version of Word (which I don't have or I'd know) provides a way to create PDFs. If you don't have it or I'm wrong, you can find open-source or public-domain PDF printer drivers that, after installation, give you a new virtual printer that saves PDF files.

As for your original question about personal Web hosts, most domain name registrars offer the service, usually free for a couple of pages, when you register a domain name. Not much left like GeoCities, these days, but the basic need for a way to share simple stuff with friends and relatives seems to be being filled these days by "social networking" sites like MySpace or FaceBook. They let you set up private areas accessible only to designated people...who, hmmm, must be members of the site--can your relatives handle signing up OK?

Hope some of that helps.