"HTTP Error 503. The service is unavailable." after SP1 is installed on windows 7

Right after I installed Service Pack 1 for Windows 7 x64 all my web-sites went done with the error "HTTP Error 503. The service is unavailable." The found by me reason is insufficient rights for ApplicationPoolIdentity user which is used by default for any IIS application. Following is 2 known for me solutions.

Option #1 – Modify the application pool by going into IIS > Application Pools > Right-Click offending app pool > Advanced Settings > Set “Load User Profile” to False.
Option #2 - Modify the application pool by going into IIS > Application Pools > Right-Click offending app pool > Advanced Settings > Set “Identity” to LOcalSystem instead of ApplicationPoolIdentity.

I prefer Option #1.