Hi, I'm looking at buying either Ipod Video(30GB) or the Creative's
Zen Vision:M (30GB). But I have many files in ogg format. I know I can
convert them to other formats, but I don't want to convert them and
neither plays oggs. So my question is: is there anyway to make either
device to play ogg without conversion? For example, thru software
updates or some third party hack. Thanks!

I'm not too sure about the Creative Zen Vision, but no iPod is capable
of playing OGG audio with the standard firmware. By installing
third-party firmware you can play most popular formats of audio,
including OGG. There are 2 third-party firmware providers for iPod
that I'm aware of, however, let me warn you first that I haven't used
either firmware option. As a result I'm unable to help on how to get
it working, bugs, etc.

Here are the third party iPod firmware providers that I'm aware of
that will do what you want:

iPodLinux
http://ipodlinux.org/Main_Page

Rockbox
http://www.rockbox.org/

Hopefully I have helped you sufficiently to make an informed decision
if you are swinging towards an iPod, sorry for the lack of info on
Creative though.