The 9000 supports a feature (the name escapes me at the moment) that smooths out the blockiness of Real Video clips. Other than that it is actually LESS of a GPU than the 8500. I belive it lacks 2 rendering pipelines but i'm sure someone with more knowledge of the details will chime in with them.
You should also check out Anand's review of the 9000 line of cards. I belive that on paper the 8500LE is better and if you are talking the retail 8500LE card with 128megs most if not all of them seem to overclock to 300/300 without any trouble at all. I currently have mine there and so does my buddy.
All in all the 8500LE is the better piece of hardware.
- J