How does a netbook hold up when when compared to more conventional laptops used by professional photographers? Pretty well actually. Rob Galbraith wrote an article comparing three conventional laptops along with a netbook (Dell Inspiron Mini 9), looking at color accuracy, how useful are they in the field, etc. The Inspiron Mini 9 was compared to a late-2008 15″ MacBook Pro, the Lenovo ThinkPad W700, and an older Lenovo ThinkPad T60.
For reference, they compared them to a Eizo ColorEdge CE240W desktop display, which is color-accurate.
In regards to the Inspiron Mini 9 itself, he found that it was useful for quite a few things – browsing photos, basic photo editing, etc., although using it to convert images in a RAW format did hammer the Intel Atom CPU and is not recommended. The only major complaint was the right shift key placement.
There is a photo included showing the Mini 9 in the bottom of a backpack made for camera gear which shows you just how small they are.
As for the display of the Mini 9, they were impressed, given the $300 or so starting pricetag. It even outperformed the MacBook Pro in one test (hue accuracy). It was surprisingly accurate when it come to colors.