I purchased the Acer Aspire One A150X with the 160 GB Hard Drive, 1GB RAM, and the 6 Cell Battery. I immediately loaded Debian on it and it's been great !! Check the link in my Sig for Various Linux Install guides on the AAO.
The Buttons being on the Side of the track pad while it looks annoying I don't really notice, the pad is so small to begin with on the netbooks that your finger barely moves to get to the buttons anyway. I was worried about that at first, but don't even notice it now.
The local store had an awesome sale on the netbooks, which is the only reason I ended up with the AAO instead of the Lenovo (they didn't stock the Lenovo). $250.00 off a $400.00 Netbook, what would you have done ? That's right, you would also be the proud owner of an AAO...
My other choice was the Lenovo Ideapad S10, Because I could get it with a Real Hard drive and it has Nice access panels to get to your RAM, and expansion cards without voiding the warranty.
Dell I ruled out due to Price and lack of Hard drive option. I didn't want to be limited to just a SSD
For nice reviews on all the netbooks check out the notebookreview site..
AAO
http://www.notebookreview.com/default.asp?newsID=4575
Lenovo
http://www.notebookreview.com/default.asp?newsID=4620
Dell Mini9
http://www.notebookreview.com/default.asp?newsID=4578
MSI Wind
http://www.notebookreview.com/default.asp?newsID=4498
Etc.. they have thorough reviews for pretty much every netbook out there. not necessarily the Linux versions but the hardware is the important part anyway, the software is easy.
I should also comment I did not consider any netbook that did not have the atom CPU.. the other options just looked plain slow..