Windows XP

For one user this folder use to be located in %userprofile%\Start Menu\Programs\Startup

Thel users profile the location of the Startup folder is C:\Documents and Settings\All users\Start Menu\Programs\Startup.



Windows 7

Personal startup folder should be C:\Users\<user name>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup.

The All Users startup folder should be C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup.

You can create the folders if they aren't there.  Enable viewing of hidden folders to see them.


Links

http://answers.microsoft.com/en-us/windows/forum/windows_7-system/how-to-get-startup-folder-in-start-all-programs/d3f5486a-16c0-4e69-8446-c50dd35163f1