I've been using an external display quite successfully for about a week. I'm using a mini DisplayPort adapter to an HDMI cable into a Dell U2711. I have a mini DP to full DP cable on its way to see if I can't get this little sputnik to drive the native 2560x1440 resolution of the U2711. I haven't had any problems with speed.

I thought randr was an AMD/ATI utility which probably won't help at all given the XPS13 uses Intel HD 3000 graphics.

As far as I know randr is an X11 extension (look at the output of

xdpyinfo) so it should work with an server that provides it, which is

pretty much all them these days as far as I know (nvidia used to not

support it). What are you using to switch displays? On my system when

I plugged in the external LCD the unity desktop would automatically

extend onto the projector and when I used something like crossover

office or virtualbox to run powerpoint for a presentation it was just

too slow. I couldn't find anyway to reliable way to just *switch* to

the external port (ie, clone). Actually disper could switch it, but

switching back to internal reliably locked up the x-server requiring

switching to a VT and restarting lightdm (or sometimes even a reboot).

I'm sorry to say, that I finally gave up and sent my xps13 back last

week when I realized I'd spent almost 3 weeks of messing around trying

to get simple things working that work out the box on my trusty old

XPS M1330 under 11.04 when I should have been getting real work done.

In Dell's favor - I don't know how of my issues are due to differences

between 11.04 and 12.04/unity and how much is specific to the xps13.

It's really too bad, it's a great little laptop -- the form factor,

battery life etc make it the perfect system for my needs. But the two

killers for me were not reliably being about to get the external

display working -- nothing worse than going to give a talk and

spending the first 5 mins of the talk fighting with the

projector. This just has to work every time in an academic

environment! And the unreliable wifi problems.

As a side note, I wish Dell had included proper page up/down keys or

at least provided a Fn key on the right hand side of the keyboard to

let you generate page up/down events with one hand! I don't know how

people live w/o that..

Maybe I'll try again after sputnik's is integrated into the mainline

kernel and really officially supported by Dell.

I don't know the exact spec of the current XPS 13, but if you will make a new one, could it support two external monitors ? As I know, Macbook Pro can support two external monitors with daisy-chain Thunderbolt connection. It'll be the best if the each resolution of external monitors up to 2560x1440.