I've given in and upgraded my machine slightly (new graphics card) so that I can sample the delights of Doom 3. It is a genuinely scary experience. The real time lighting is very effective (although even with my new graphics card I'm probably still not seeing it at its best).

Number one son says sniffily that Doom 3 is a prettier version of System Shock 2 with slightly poorer gameplay but to me the impression of being in a stricken space complex under attack from unleashed hordes of hell is very well realised and quite engrossing. I'm not sure how much further my abilities will get me (or if I have the nerve to go there anyway) but at the moment I'm having fun.