I stumbled on this today when I received some machines from Dell at my work.
First set up a log in then enter the service tag numbers for your machines.
Once that's done you can click on the number for a given machine and get detailed information on it such as processor, RAM and other bits of news. Most importantly to some of us it gives the date it was shipped from Dell.
No more having to guess when a machine went into service.
Bye for now,