I do not see the reason to update to win7 while all existing applications are running happily with winXP. Under M$ limitation, it has limited all netbook manufacturer not expand further screen more than 12" because it should already been phased out if there was no netbook two years ago.
For any given application,if it can run happy with winXP of 1G or 2G ram, it is equivalent with win7 of 2G or 4G or more at similar running speed.
If you really need win7, it is better to been run on ION or any hardware with better graphic hardware.
since most linux os run smooth with netbook, it is double that win7 could really replace winxp to compete with low price of linux os.