Just FYI, I bought a Zalman VF700-AlCu for $25 at Fry's, and my AIW is now running at 605 core, 640 memory (1280 DDR). That's up from the default of 500 core, 480 memory (960 DDR) -- a 21% increase in core freq, and 33% for memory. Compared to the X1900XT, I am 3.2% slower in core (605 vs 625) and 12% slower on the RAM (640 vs 725).
This is just using ATITool's simple "find max core" and "find max memory" features, with no overvolting. The memory can go *slightly* higher, but the core seems stuck at 605 -- getting it any higher will cause a crash (not a system crash, just a video-card crash with a pop-up from the ATI driver saying that the card was reset). I don't really have much time to test it in games right now, as I'm going out of town this week and have to finish up on some work before I go. I will report back later with more info if I get it. I would also like to run some benchmarks with AA with the memory at stock speeds and overclocked speeds.
One thing that I forgot to do is try o/c'ing with the stock cooler. I would have liked to get a baseline of temps too. Under load, the GPU gets up to nearly 70 deg C. That seems kind of hot to me. If anyone else with an X1900 AIW could just fire up ATITool and tell me what their temps are, I'd appreciate it. N/M, it looks like GT and XT cores hit 90C easily with normal cooling, so I've got nothing to worry about