Cat puzzles

I'm sitting at computer A. I'm just about to move over to do something on computer B, when cat C appears through the window and sits on chair B. I move cat C from chair B to chair A and sit down at computer B. I realise I need a CD from computer A. No problem, I can reach the eject button from here. I eject the disk. Cat C gets off chair A, and comes to sit on my lap at computer B. CD in hand, cat on lap, I can't reach the CD tray of computer B. I try to manoevre chair B over to CD tray B, but the chair's too wide to get through the gap between desk and bookcase. I evict cat C from my lap, get up and put the CD in CD tray B, and go back to sit in chair B. Chair B is slightly off to one side instead of directly in front of monitor B; it obviously slid over as I got up. Cat C is walking around the patch of floor directly in front of monitor B. I move chair B towards monitor B very slowly in that hoping-she-gets-the-hint kinda way, and eventually she wanders off to mooch around near chair A. I start to relax and lean back in chair B only to find cat C is sitting in chair B behind me. Fortunately, she was only there en route to the outside window sill, where she's sitting now, washing herself and occasionally giving me hurt looks.

Solutions to cat puzzles?

I've cleared some of the superfluous stuff up in the study, which means there's now room to swap the two desk chairs over without having to lift them. Cat C is still not entirely happy about this; her chair of preference is the one next to the window. Which also happens to be the one I'm mostly sitting at. Whenever I get up, she leaps over from the inferior chair to the window one (the two chairs are pretty much identical in everything but their position in the room). We tried her sitting on my lap for a while, but she's not too happy about me typing, and I'm not too happy about her digging her claws into my thighs whenever I shift slightly to avoid my legs going to sleep.

My next solution was to place the desktop fan on the window chair when I'm only getting up for a short time - to get water, or to answer the phone or something - which works quite well, because the base of the fan takes up too much space to leave any for cat C.

There's still a problem, though. She spots me returning to the chair and removing the fan, and in the time between me lifting the fan and sitting in the chair, she's there. So currently she's stetched out along the back of the chair, and I'm perched on the edge. She seems to be comfortable. I'm not.