Reinstall Vista Home 64bit

Quick background.  This is a StudioXPS 13" with Vista Home Premieum 64bit system.  Only 1 profile set up, as Admin.  Not on a network.  The password for that one account has been lost/forgotten - looking to reinstall using the Factory disc's provided.

After multiple attempts to reimage the system back to original factory image using Dell provided disc's, no luck.  Is it possible to provide a step-by-step to reimage system using provided restore image, without logging into only profile (because it is locked without a password)?

Thanks!