Clippit

Clippit (usually known as clippy) is the not-so-annoying office assistant from Office 97-2003. He gets unfair reviews, though not as unfair as the hockey puck mouse.

Why he isn't annoying
Him constantly popping up is actually music to my ears!

Other office assistants
There are many office assistants out there, but the best has to be tied between Links (2000) and hoverbot (1997) because Links is cute and Hoverbot is so advanced!