Apple Lisa II
Apple Lisa II, the second incarnation of the Lisa, introduced in 1983. The Lisa was the first personal computer with a graphical user interface. This particular model has a 2MB (count them, two) memory expansion board, and a whopping 10MB hard disk.
Bits and pieces: manuals, original system disks, ImageWriter printer, gauze anti-glare filter (removable).
Amazingly, at going on 20 years old, she still works. Photos here.
Also, apart from the GUI, the Lisa has some innovative features unusual in a 20-year-old personal computer. The power switch is a "soft" one. When you press it, the Lisa saves all open documents, and then turns itself off.
The brightness of the monitor is controlled in software.
Pre-emptive multi-tasking, very ahead of its time.
Serial Number: A3342519