What version of ubuntu did you install?
I think the sound drivers were updated for Dapper quite a bit, as I was having some problems on my desktop PC (Audigy card) when running Breeze, and now all seems to be fine with Dapper.
You may want to take a look at the following:
http://users.ece.gatech.edu/rbutera/omnibook900.html
I found it at:
http://www.linux-on-laptops.com/
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Also, I am about to install Dapper (Server) onto my old Omnibook 900; want to make a small, personal web page/server with it. Do you have the original Ethernet PC card that came with it? If so, did it work out for you?
I do not have an Ethernet card for it, and I'm searching through eBay for one. I already found the F1643A which is a "designed-for-Omnibook900" Ethernet/Modem PC Card from Realport. I am just curious to see if you have something similar, whether it worked, and if I should spend money on such 'unique piece of hardware' ?
Maybe we could help each other make all hardware work properly?