88*c is hot, definately, and nearing the temperatures where GPU death is almost a certainty, but, my 6600 reached 90*c when overclocked and under load... it seemed to run quite a bit warmer when the Nvidia driver was fooled into thinking it was a Quadro too, which I used for about a month, and I believe it would reach ~95*c. I believe it reached about 103*c on occasion in the summer, but only once or twice.
Ended up selling it to help buy my new card, the guy that bought it never complained, so it's probably still functional.
Although I don't recommend keeping it at high temps like that for too long, it's just not healthy, unless you really don't care, in which case, it's fine.
EDIT: Also, that fan near the PC isn't healthy either... they can produce magnetic fields when spinning, and mess with CRT monitors, and anything using magnets (so, of course, HDD and FDD). I don't know if it's enough to kill a HDD, but if I were you, I'd rather not find out.
Yeah, I know, PC fans make mag. fields too, but since they're smaller, it's probably not enough to mess with monitors, and magnetic media.