When describing use cases, or generally discussing pros and cons of a design, it can be helpful to define some "fictious users" so we can refer to them by name instead of "picturing" them anew every time we need them. Making them "global" will help project communications, so here they are:

Joe Average
Working in an average office cubicle with an average computer doing an average job. He has a computer at home that he uses for e-mail, web browsing, occassional games and other average stuff.
Andrea Maxframes
She always gets herself the latest in 3D and sound equipment to get the ultimate gaming experience. Overclocks her CPU and is always looking for some way to tweak another fps from her system.
Toni Administrati
The guy who has to administrate some big company's office computers and servers. He is not a wizard who knows every file in /etc by heart, but someone who did just enough reading to do the everyday job. If the system hickups, that means a wrecked weekend for this poor chap.
Mr. Anykey
The guy in the urban legends about really clueless users. He does (usually) know where the power button is, but little beyond that. Mr. Anykey is not 'stupid', but computers are simply a mystery to him. He is really afraid about what could happen and never clicks around in the GUI if he is not sure what he is doing... except for the moment when he thinks he knows, which is when he breaks things badly.
Sarah Progmatzki
Software Engineer, coder, hacker, whatever, power at your fingertips. She runs her editor, two compilers, an IRC client and a newsreader at once, half of them on a remote system, and has her system perfectly tuned to her whims.
Mrs Typeright
Not really Mr. Anykey nor Joe, she is a one-application specialist. She knows virtually everything that could be learn about the program she uses (even more than Sarah would know), but she is almost as clueless as Mr. Anykey once you take her out of that program.
Frank Freebyte
He's the hard-core Linux geek who actually likes his shell cryptic, his GUI inconsistent and his projects forking every which way. He also considers us evil incarnate because we do not endorse the GPL. We're not here to please him, but we have to handle him.