Jen knows nothing about IT, she only got the job because she said she had extensive experience of computers like using mices, clicking, double-clicking, and that thing that goes on the floor... the er hard-drive?
As well as being their line manager, Jen is Roy and Moss's agony aunt, relationship coach and guru about life outside the basement. Not that her life is going particularly well, it's just better than theirs.
Jen's love life is more varied than Roy's and more existent than Moss's - but not exactly successful. She once caused a very promising date to lose a fortune on Who Wants to Be a Millionaire (not even dinner at Messy Jo's could fix this one), she dumped one boyfriend purely because she didn't like his name (what's wrong with Peter File?), and she once spent an evening sitting through the very gay gay musical 'GAY!' only to discover her love interest was, in fact... homosexual.
If all else fails, she could always give in to Douglas' advances - but she would sooner clobber him over the head with the Internet first.