Comment 17 for bug 570765

+1 for Nicolas' point... this issue, small and seemingly easy to work around as it may be, is a huge factor in the user experience, especially from the standpoint of the new user. For that reason, this is a critical bug, even though it does not directly impact Ubuntu itself.

Even the appearance that 10.04 has deleted the new user's Windows install is, IMHO, anathema to the entire drive to capture new users and bring them to the Linux world.