If you are facing a problem that you can't sign your project using VS 2008, this is not because there is a problem in VS 2008 but this is because the User Access control (UAC) feature in Vista. The User Access Control enabled in your system, you have to disable it to enable signing to your assembly in VS 2008.
If you can't publish your project using ClickOnce deployment in VS 2008 and your are getting an error message : "publish aborted, can't create a default certificate"
The cause for above 2 errors messages are because of the UAC is enabled.
To do/fix this:
1) Open Run windows in Vista: Accessories -> Run.
2) Type MSCONFIG command.
3) select tools tab, select Disable UAC and click on Luanch button.
4) Reboot your system (Important).
Once you reboot your system, open your project and you will be able to sign your assembly.
Hope it helps.