Things may have changed quite a bit since I purchased my Dell Mini back in September, but I'd agree that based upon my research THEN that it comes down to the Wind or the Mini. What ultimately sold me on the Mini was the passive cooling (no fans) with the corresponding potential for better battery life and I have to say that it works as advertised and never really gets that hot.
I purchased mine with 512mb of RAM and then upgraded on my own to 2GB (At the time Dell didn't offer over 1GB) and with SDHC cards dropping in price it was easy to cheaply add 16GB of 'internal' storage via the memory card slot.
Only really concern with the Mini is a somewhat awkward keyboard (some of the keys...especially the ' key are in odd places) but you get used to it pretty quickly.
If the potential for a cramped keyboard bothers you it might be worthwhile to wait for for the recently leaked Mini 10 to become available. Looks to be around the same size as the 9 (Unlike the currently available Mini 12) but will sport an edge to edge keyboard.
The Great Apple Netbook Experiment, Part 1, What to Buy