Are you kidding me man? The x800XL is the most cost effective 16 pipeline card out there right now, and gives higher core speed GPUs a damn good run for their money. Not to mention it uses a 110nm process versus the more common 130nm process.
You guys are fighting over nothing, I've said it multiple times and I'll say it again:
$200 - 6600GT
$300 - x800Xl
$400 - it really doesn't matter, and anyone who wants to argue about a two framerate edge is probably in the same group of people who think lower latency RAM has an effect on bandwidth.