Thank you for contacting Hewlett-Packard's e-Solutions Center.
This email is in response to your HP Compaq nc6400 Notebook PC with respect to the Incident ID xxxxxx.
From the email, I understand that HP Protect tool says not compatible with Windows 7 while running the Windows 7 upgrade advisor.
Gareth, I will be glad to assist you in providing you the required information. I would like to inform you that when new operating systems have been introduced in the past, Microsoft has offered an upgrade program that HP made available to its customers. At this time, HP expects there will be a similar program for Windows 7. Microsoft has now announced the timing of the upgrade programs or the official launch date of Windows 7 as October 22nd 2009. Hence, the drivers can be expected closure to this date.
Hence, I request you to stay with Windows Vista or XP till any further notice.