[zx10guy]

Not impressed with NetBooks in general.  When I went shopping for a ultra mobile PC solution, I ended with two choices:  the Sony P series or the Fujitsu UH900/UG90N.  I ended up with the Fujitsu UG90N which I had imported to the States from Japan.  The UG90N runs full Windows 7 and has the following specs:  Intel 2 GHz Atom processor, 2 GB of RAM, 62 GB SSD hard drive, Intel wireless N card with builtin WiMax adapter, and multi-touch touch screen, 2 USB ports, and a SD card reader.  I got the optional extended life battery which I have gotten about 4 hours of use.  I also picked up the optional 100 Mb LAN and VGA dongle.  I have the full Office 2010 suite on the PC and have not run into any issues with running software of this type.  I absolutely love what the UG90N brings to the table...the ability to compute on the go without making major sacrifices.  Here is my mobile computing setup:
 

 

[zx10guy]

I forgot to add one other comment about SSD drives.  They really don't save you all that much power; particularly if you leave your laptop/notebook/what have you in standby a lot.  I find that leaving my UG90N in standby doesn't get the same battery mileage I would get compared to a laptop with a standard hard drive in it.

 

[MuuMuu]

netbook sounds like a silly idea if you're wanting to run some of the heavier programs on the thing.  You'll probably be better served w/ a midrange/lowend light laptop from acer/asus that use lower-voltage C2Ds and such.  Price isn't too far off from a netbook either, and you'll have 12-13inch screens on a 3-4lb system.
 
An alternative would be a superlight system that you use and remote to a faster PC for the more rigorous processing duties.  If it involves lots of CAD editing and such this won't work, but a lot of those programming suites will work just fine.  For lighter duty work you can do this on an ipad and home PC too, effectively allowing you to have a PC that can do a lot of things that the ipad can't.