I recommend an X series thinkpad. x40 although X60 and up would be ideal. It'll be in the $300-600 range used, and lightyears better than what any netbook would offer
The X40/X41 might be cheap, but it is limited to a proprietary 1.8" drive and 1.5GB RAM. It'll be a slow drive around 40GB 4200rpm or you can spend money for a SSD.
I suggest the X61. It'll support up to 8GB RAM and takes regular laptop drive. On ebay, I've seen it slip out for $300.
I suggest the X61. It'll support up to 8GB RAM and takes regular laptop drive. On ebay, I've seen it slip out for $300.