Purely because we haven’t mentioned it and probably should – er, as above. Should you buy it? Hmmm. It’s pretty good – a far more pleasant desktop environment than Vista, and noticeably nippier in certain areas. But, long story short, it ain’t gonna make a blind bit of difference to your everyday videogaming, unless you’re into running framerate counters at all times and watching ferociously for an occasional 1-3 frames per second difference. If you’re buying a new PC though, make sure it comes with 7 rather than Vista. Oh, and do install the 64 bit version – very few compatibility problems (really old games are the most likely thorns in the ointment) and it means you can use more than 3Gb of RAM.
Of course, knowing our audience, anyone who’s genuinely interested in Win7 has probably been running A Version for months anyway….