in my experience a good alternative for cheaper setups would be m-audio interfaces. i had amazing performance (on a really basic desktop) with ubuntu and an m-audio delta 1010, in Pd and jack. are these temporary installations though, or are you permanently setting them up with an ultralite? only ask because the ultralites retail rather expensive, you could build a cheap linux machine and throw on an m-audio interface for not too much, and then that could be a permanent installation.
just speaking from experience, unfortunately i have none with MOTU besides on OSX. googling around a little bit it sounds like they're not the best choice for linux (http://ardour.org/node/156, albeit an old post) and they are tied in tight with OSX so you can understand why linux support's not on the top of their list. bug the ubuntustudio guys about it maybe, *buntu always worked amazing with Pd for me... what distro were you thinking of using?