Ok, so I just spend a few whistful hours trying to work out how to modify the "All Users" profile on a Windows Server 2008 system. I wanted to add a program to run at login (e.g. in the Start Menu|Programs|Startup directory) for all users that login, but things are now a bit different with Vista and Windows Server 2008.
I have found quite a few people asking similar questions on the Internet but no one seems to have offered a solution that works so I thought I'd post my findings.
Firstly, for those who haven't hit this before, the "C:\Documents and Settings" directory where user profiles are stored in Windows XP and Windows Server 2003 systems has changed to "C:\Users" in Vista and Windows Server 2008. (I regularly encounter XP users who have upgraded to Vista getting confused by this one)
So now in Vista and Windows Server 2008 the "All Users" directory in the C:\Users directory is a hidden directory so you will need to "Show hidden files and folders" in Windows Explorer by going Tools|Folder Options|View to show it.
Once you have visability to the C:\Users\All Users directory you will notice that it is just a shortcut then if you try and access it you will get an "Access Denied" dialog box. Real Handy.
Looking at the properties of the "All Users" directory shows that it points to the C:\ProgramData directory (this is a new system directory that did not exist in older versions e.g. XP etc). The C:\ProgramData directory is also a hidden directory but if you have already done "Show hidden files & folders" as above then you will see it.
The C:\ProgramData directory has a sub-directory called "Start Menu" but you will get Access Denied on this one too.
This is now getting a bit long so lets go straight to the answer ... the Startup directory I needed is now at "C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup"
So essentially, under Vista and Windows Server 2008 the "All Users" profile is now manifested as the C:\ProgramData directory and there are shortcuts from the C:\Users\All Users directory to the new location for compatibility reasons but in most cases you will get an Access Denied dialog box when you attempt to access the shortcuts but you will find most of what you are looking for under C:\ProgramData\Microsoft. You can also access this via C:\Users\All Users\Microsoft
I can't offer you any explanation as to why the All Users profile underwent such a change in Vista (and Windows Server 2008) but for now I have solved my challenge and have got my startup program working for all users.
I hope this helps those similarly confused ...