There are ways of getting around not using the CCC and .net 1.1, but none of them are really acceptable (IMO) with an X1800XT.
-ATI tray tools works with R520, but you have to disable overclocking. This sucks because I can reliably run my XT at 690/800 with the CCC.
-The regular CP doesn't support the Adaptive AA, which is one of the cooler features of the X1k series.
The best solution that I have come up with so far is to run ATI Tray Tools for IQ adjustments and ATI Tool for OCing. However, this is actually more annoying than the CCC + .net to begin with, and just sticking with the CCC is what I have choosen to do with XP 32-bit. It looks like this may be to the only option for XP x64 though, since it doesn't look like the CCC will run on x64.
I really like my Radeon (and I don't want to start a war), but this is the type of stuff people are talking about when they say that ATI drivers suck. ATI releases a driver package that supposedly works on XP x64, but part of it requires .net 1.1 which doesn't exist for XPx64... Ummmm, ok... WTF? I understand that the actual driver is not the problem, but the CCC is a pretty integral part of the driver for X1k cards, so it really doesn't make a difference in the end...