Recently while surfing,  i found this image which gives a good answer for the above question.
As Dell’s Jay Pinkert said last year : ” The Linux powered Dell Mini 9 netbook has been comparably successfully considering that one third of the sold units where shipped with Ubuntu Netbook Remix.”

This is a screenshot (Click on image for a larger Version) took by one from germany (author of linux-netbook), he went to dell webshop for buying dell  mini notebook. Ubuntu 8.04 was pre-selected without another option to choose from.But the strange thing was that , it was  the logo of WINDOWS VISTA that was displayed right to name “ubuntu 8.04″.
and the logo links to Dell’s page about Microsoft Windows Vista.

Is this a mistake or they did it purposefully? We have to ask!!