X850XT was great because it trashed 6800 Ultra for the same price, but against 8600GTS - not even close! For that cathegory best bang for buck is X1950 PRO - will outperform the 8600GTS big time.
1. It didnt trash it, not by a longshot, remember the original competition was the X800, whoch was about on par and all the X850 was, was higher clockspeeds.
also keep in mind the 6800Ultra was first to the market, by a good couple of months as i remember it, and the Ultra Extreme could par our beat your X850.
i know, i did own a 6800Ultra OC AGP, and bench it in my rig against a X850XT (non PE) and it came out on top.
trashed? hardly. competed well with? yes!
and go the 8600GTS, these cards were a little beaut in their day, i had GT's in SLi, awesome tweaking fun.