Make a prompt show up on users desktops as controlled by server

[infinitizon]

Hello guys,

I want all my users to get a prompt (with a click-able website link in it) as soon as they switch on their systems.

How can I get this done?

 

[toolbox212121]

Are you running a domain? What OS are you running on the desktops? Do you want the link at bootup or login?

 

[infinitizon]

I am running a domain. The DC is Win server 2003; the users have different versions of OS ranging from Win XP to WIN 7.
Also, I want the link at login (i.e as soon as you logon to the domain).