What a difference a color can make. The Sapphire Blue Acer Aspire One netbook tops the netbook sales charts on Amazon.com and on Walmart.com.
On Amazon the Blue Acer Aspire One 8.9 inch netbook (Windows XP) with 160GB HDD and 1GB RAM is in the lead selling for $399.99.
On Walmart.com the Acer Aspire One (Linux) with 8GB SSD and 512MB is on top selling for only $338.

The 160GB Windows Acer Aspire One most likely would also lead on Walmart, but it is sold out.

The Acer Aspire One is a sleek looking netbook, but I think their key to success is the low pricing. The Acer Aspire One is way cheaper than the Atom based Asus Eee 901 PC.
Since Dell only sells the Dell Mini 9 directly it is not clear if sales of the Dell's netbook can keep up with the Acer Netbook.