Since you are new to linux, here goes:
Best way to run Ardour and JACK is with Realtime Permissions. I also use ubuntu although 8.04 LTS.
In /etc/security you should have a file named limits.conf paste this at the bottom before the “# End of file” line.
@audio - rtprio 99
@audio - nice -10
@audio - memlock unlimited
What that does is that it gives all users that belong to the group “audio” the proper permissions to run Jack in RT mode. Usually you have to check that your user account belongs to that group, usually in ubuntu all desktop users are added automatically to it.
Then reboot and in qjackctl (Do you have qjackinstalled? If not please do) and in Setup check Realtime and you could leave the priority to default for the meantime…
First try with that and see what happens…
You will have to do a lot of reading on how and why you should install the RT kernel, its included in the ubuntu repository, although sometimes it’s just no 100% properly built for audio, but should do the work. I have gotten to the point where I had to learn to compile my own kernel with or withour RealTime support, because the ubuntu maintainers I really don’t think they can tell the difference from their head and their ass…but that’s another story.
You will also have to do some reading in how to configure JACK, remember to use qjackctl. Look for other peoples tips especially here in Ardour forums with your specific Audio card.
Last but not least, you should also in a future learn how to download the RAW source code of Ardour (and maybe any other program you want to use), and compile it yourself, that is if you really want bleeding edge and STABLE versions without depending on the ubuntu repos. I know this sounds very intimidating, but believe me and take my word for it. It will give you a lot more knowledge to become a more advanced linux user and besides it’s not as hard as it looks, actually it becomes so much fun, because the packages in the repositories are just too old, unstable and soetimes don’t have the support for specific thing you might need like LV2 and VST plugins. I think also the export bug you have, is because you are using the Ardour from ubuntu repos, I’ve seen this type of bug before.
Finally, please use the forums here. I mean use the search option, and browse months back. You will see a lot of linux-ardour newbies (I should pop somewhere in the crowd also crying for help and guidance), but you should be able to find all sorts of good info to set you up.
Good Luck and don’t give up. When you get a hold of this things you’ll notice with time you will never go back to windows again. And you can forget about that expensive MAC.