two weeks ago I got the 6 cell battery that I ordered way over a month before. Now my netbook runs for about 4 hours while using WiFi, this is not great but good enough. Also with the two batteries I get a total of 6 hours. Note, this is Linux not Windows.
The battery is one of several upgrades I put into this device: the first thing I added/replaced was the really bad passive cooling, I replaced it with a 20Euros thingy (that works really great and lowered the temperature by 5-10C). Second was the WiFi card. I replaced the RealTek crap with a Atheros a/b/g from eBay, again 20Euros. The battery was 80Euros. All in all I paid 580Euros for this netbook. This is not really cheap but the thing I really like is the form factor and a decent notebook/laptop that has the same size and weight costs about 1000-1200Euros, so I'm happy :-)
The only thing that still bugs me is the touchpad. The sentelic thing used by my Wind is no competition for the synapics touchpad in my 4 year old Thinkpad. Also I kind of got used to it by now.
Looking at the other netbooks that are currently available the MSI Wind still is one of the best. At least for my needs.