the hardware and software for the xps 13 with ubuntu 12.04
min. 8GB ram. Now i have a Sony Vaio with i5. I upgraded from 4GB ram to 8GB ram. Now all works fine. Before, my system was very slow, when i developed with eclipse and had to test some things in VMWARE at the same time. Now, all works fine. So I think, that CPU-Frequency (i7 or i5) does not matter, but 8GB ram is a must have.
The secound thing, an ultrabook should have, is a min. resolution of 1440x900 like the mac book air.
The preinstalled software should be: eclipse and vmware. I think this two programs are mandatory for every dev-notebook.
If all these ultrabook has a price under 1500 EUR it would be a very attractive dev-notebook.
I would buy such a notebook if it would be available to buy it for Austria.