I have used an Acer Aspire One to review shots and used PS CS4 on it. Was slow with CS4 and slow loading ViewNX. Once ViewNX loaded it was fine. I ditched the netbook and just went back to my Dell M1330 because of the processing power and screen. The netbook monitors are crap. The M1330 has an amazing screen and just about as powerful as a standard desktop. Plus it barely weighs any more than the netbook.
XPS laptops are fine when they work. But they're nowhere near as reliable as a Latitude... not as reliable as an Inspiron either I'd say.
They use the same mainboards, cpus, ram, optical drives, and other internal parts. Plus they have metal hinges and a more rugged exterior. So I don't see why they would be any less reliable. I've had 2 XPS laptops now and they are absolute tanks.
There's absolutely no comparison in build quality. Latitude is far superior. And internally they're not the same. They're sparkly and fancy and attractive. But if you're looking for a workhorse run far, far away from them.
I'd also add - the M1330 max resolution isn't fantastic either. Again; inferior to a similarly priced Latitude. Obviously it's smaller though - the price you pay for portability I guess.