Third that FastStone. It more now than it used to be. It has more editing tools, and a few other options. It's footprint is small so it should work well with your netbook.
The newest version newest features:
Quote: Version 4.3 (January 14, 2011)
Added Clone Stamp and Healing Brush
Added "Auto-Adjust Colors" to Colors menu. THANKS to Andras Horvath:
log69.com
Added "Adjust Lighting" to lighten or darken shadows and highlights
Added "Adjust Levels"
Added "Adjust Curves"
Added USM (Unsharp Mask) option to Sharpen/Blur
Added Sketch and Oil Painting effects
Added outward-pointing tails to text objects in Draw Board
Now images in Slide Show Builder, Multi-page File Builder, Image Strip Builder and Email list can be drag-and-dropped to rearrange the order
Supported EPS format by displaying the preview image
Updated the RAW format library. Sony SR2 raw format is supported
Improved memory management to handle larger images
Other minor bug fixes and improvements