We will see.....
The problem is that when people go into a store they want Windows because that is what almost everyone else has and it's what they know and what they have used at home and work. If it has linux on it they just think "what the heck is that?" and ignore it.
If they manage to get it on some big brand machines then they need to try and make sure it gets marketing behind it. The Linux distro makers obviously don't have anything like the money MS has but they could make sure a machine is sent out to reviewers (TV, printed and online), invite them around and explain the benefits and generally show it off. If they can get people interested and showing them off on a prime time gadget show and big online magazines then it could gain some momentum.
Windows 7 is a good OS and it will probably sell by the lorry load but I would be very happy to see Ubuntu or another distro make their case to the public.