In an interview with ComputerWorld a few days ago, Dell said that "sales of the Linux-loaded machines are encouraging". However, they refuse to give out any specific sales figures. "A [sales] number is not going to validate it as much as our actions to date,", they said. As for the lack of promotion, they claimed that Linux enthusiasts will find the machines anyway, promotion or not. "If you know Linux, you're going to know we sell Dell products with Linux on them." They did not exclude the possibility of Linux-centric advertising in the future.
Personally, I always feel that if a company has a hit on their hands, or even reaches sales estimates, they will be shouting it off the rooftops - if they decline to give any detailed information, or use fairly vague and indeterminate terms like 'encouraging', it usually means that either sales are so-so, or that they are downright bad.
Interestingly enough, even if Dell were to give more detailed figures with regards to the amount of machines it has sold pre-loaded with Linux, we still would not be aware of how many Dell machines actually have Linux running on them. How many of you have bought a Windows Dell laptop, only to remove Windows afterwards, replacing it with Ubuntu, OpenSUSE (or whatever your choice of distribution may be) instead?
Which brings us full circle to the usual problem when it comes to 'counting' Linux machines. Who is keeping track of all the enthusiasts who download and install Linux?