I had the same decision as you and I went for the Radeon 9000PRO. The major difference is that the 9000PRO has only "one texture unit from each pixel pipeline". This will result in a very minimal performance drop, when compared to the Radeon 8500 LE 128MB, when playing games that use multi-texturing. One game coming up that does is UT2003. If you take a look at
Anand's review of the Radeon 9000PRO, you'll see that in some benchmark results in UT2003 Performance Test the Radeon 9000PRO comes out on top, and in others, it falls short due to multi-texturing. The Radeon 9000PRO also has some enhanced features that in some situations bring it above the 8500LE. So, it's up to you. I felt better about going with the newer product at the risk of losing a few frames in upcoming games.