Obviously you have not seen many HPs. They have gotten better than they used to be, but some of their mini-tower cases are very cramped (as in remove the hard drive and optical drive if you want to get at the RAM or power supply connector). A fan on the video card isn't going to help much if there is no air flow to start with. Are they up to 300W power supplies as standard now, rather than something like 120/160W?
went to best buy the other day and the smallest they sold was 300 watt.So yes thats pretty standard and would go as far as saying 350 watt is standard now.