As long as you've got a legal version of the Windows 7 installation files, put them on a bootable DVD, then boot from the DVD..
On the other hand, if you're looking to perform an "upgrade" install, (hopefully, you've got a compatible upgrade version of Win7), you'll need to get the password. Try Googling the "NTPassword" program to get that done. A link is below:
http://pogostick.net/~pnh/ntpasswd/
Hope this helps.
Grif
Hi,
I got a used pc and the darn thing is password protected in vista.
I figured it would be no big deal since I would be installing windows 7 over it.
what I did not think of was, I have win 7 on a flash drive and I can not use this to boot off of
In the bios it would not let me use the drive as a bootable device.
soooo I would need to install it over Win Vista THROUGH windows. but of course I cant get the heck IN windows.![]()
any help would be appreciated!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic