An anonymous reader writes:
The answer: Less than you'd expect. Dell today will start selling its first three models preloaded with Ubuntu Linux: the Inspiron E1505n, a 15-inch notebook; the Dimension E520n, a middle of the line desktop; and the XPS 410n, a desktop that starts out with virtually identical specs to the Dimension, but can be customized with more gaming-centric hardware (though you hardly need hardcore gear to play the games available for Linux).
I did my best to customize comparable Vista machines with the same equipment that Dell lists for their Linux equipment and here's what I found:
Dimension E520 — Vista Version $729 / Linux Version $599
XPS 410 — Vista Version $899 / Linux Version $849
Inspiron E1505 — Vista Version $728 / Linux Version $599
So the average price savings for choosing Linux over Vista: $103. A full copy of Home Basic will set you back $199, while Home Premium costs about $239. Obviously, though, Dell doesn't buy Windows at retail prices, so perhaps this average savings is in line with their actual costs.
http://blogs.pcworld.com/staffblog/archives/004474 .html