I hate those small netbooks that are more toys than real laptops! Here is what I suggest instead

Step 1 Get a used ThinkPad X40 or X41 (+- 400$) on Ebay. Their processor is way faster than current Intel Atom, perfect keyboard, build quality you cannot find anymore and a nice 12 inch screen. They weight around 1.2kg with 4 cell battery of 1.4kg with 8 cells. I owned a used laptop store 1 year ago and IBM X series is the only notebook I never had a return (and I sold hundreds), they are extremely reliable and soo quiet.

Step 2 Get a UDMA 8GB compact flash - Lexar professionnal 300x are good (100$)

Step 3 Get a compact flash to ide adapter on Ebay or from Addonic (5 to 25$).

If you need a little more storage, you can fit a Secure Digital card in an X40-X41. If you need a lot more you can always use external hard drive or network storage.

Step 4 Install Xubuntu 8.10, the interface is much lighter than Ubuntu and it will work out of the box... For coding install Aptana.

Call me crazy but I went from a Quad core 3.2Ghz/4GB RAM/4x RAID 0 storage to this tiny Netboot for daily usage (24 inch monitor when not on the road) and Im happier than ever!

More info how to use Compact flash in X40 - X41 : http://www.thinkwiki.org/wiki/Compact_Flash_boot_drive