I've updated my sidebars and have added a new list on the left for several places you can get free OpenOffice.org and Microsoft Office templates. Also I've listed places to get free fonts and clip art. I fond them all just by googling, free templates, free fonts, and free clip art, so please feel free to go out there looking yourself if these sites don't give you everything you need.
Templates -- Keep in mind that most templates in MS Office will open up fine in OpenOffice.org. Start OpenOffice.org, choose File > Open, open the template. Then choose File > Templates > Save, give the template a name, click OK, and it's now an OpenOffice.org template. To use it, just choose File > New > Templates and Documents. (And if it was a Powerpoint template, it will show up when you choose File > New > Presentation.)
To convert a bunch of MS templates to OOo format, just choose File > Wizards > Document Converter and follow the wizard through. Then choose Tools > Options > OpenOffice.org > Paths and, for the Templates line, just add the location of the converted copies that the wizard made.
With Powerpoint templates you do need to do an extra step because of an annoying naming thing that MS does.
Here's some more supplementary info on templates.
Clip art -- If you're associated with a school, company, etc. then centralize the effort. Just get one person (a student with a period free or an intern, ideally) to download the clip art, organize it, and add it to the gallery.
Fonts -- Lots of new fonts are a good way to help smooth the way for apprehensive new users. Plus, they're just fun. Download the ones you want for your operating system and copy them to the appropriate directory, such as C:\WINDOWS\FONTS. They'll then show up in OpenOffice.org.