set print to pdf as your default printer in the printer settings.
then highlight the files you want to convert, right click and select print. it'll open up multiple save as windows for you to name the files and tell where to put them.
about as easy as i can think of to accomplish this without going nuts with scripts and such.
there's also a ton of free online convertors that will batch convert as well. if you trust your stuff to be out onto the web. prob a local one as well but i've never used one so can't vouch for any personally.