i'm a member of the bf2 *Mine* clan, and our 30 or so members use a wide variety of hardware and operating systems. over the last couple of months, nearly all of us have been having intermittent punkbuster problems. it doesn't seem to matter which flavour of windows we are running - sometimes myself i can play for hours with no problems, then suddenly start being kicked every few minutes. i really don't think it's to do with 7 specifically.
punkbuster really do need to get their act together - they simply aren't busting as many punks as they should be! the innocent get kicked and punished, but the haxors still get through - literally almost every day we suspect and later detect (using screenshots) cheating low-life scum who seem to easily circumvent the checks.
it's gotten to the point where i really don't play bf2 as much as i would like - i'll stop now before i get too angry!