I have a 1 month old base 09 mini, The 1GB is enough for watching HD vids etc without any issues. My only issues are with the super poor quality disc drive that takes two hours to install iwork & ilife each.
I would actually go to 2GB. Mine should be arriving this wednesday, and from what I've read and photo I've seen for opening it up, its something that you just want to do only once and get it over with but I'm going 4GB.