oh good news for who that have the R580 aka X1900 series
here's a fantastic Space Screen saver, packed with High Dynamic Range, Depth of Field Blur, Motion Blur, Soft Reflections, Soft Shadows, Pixel Shader and Vertex Shader 3.5 effects to the max
http://ati.amd.com/developer/demos/rx1900.htmlWhy ShaderModel 3.5 since that HDR & FSAA are combined

it really astounded myself on what a single X1900 XTX can do, man some parts in this tech demo were like Crikey it's so realistic!
As the screensaver gave me such a perfect impression of what a Comet/Metiorite is like in flight close up or how a supernova is created by an exploding star, heh when that happens you get blinded by the High Dynamic Range effect!

Anyways it's a real must, if there are lads with X1800 cards I'm quite sure it will run on those as well since an X1900 class can do the same as an X1800 class, the only thing is that the X1900 XT 256/512 /XTX have 3 times the PixelSHader Processors the X1800XT 256/ 512 have, but I'm quite sure it will work 8)
heh about the P3 experiment, it did work with the following cards in AGP x2:
ASUS AX800XT Platinum Edition AGP 256MB GDDR3
XFX GeForce 6800GT Dual DVI AGP 256MB GDDR3
Leadtek GeForce 6800 AGP 128 MB DDR
Hercules 3D Prophet 9700 Pro 128MB DDR
Club 3D Radeon 9700 Pro 128MB DDR
Connect3D Radeon 9800 Pro 128MB DDR
Gigabyte GeForce FX 5700 AGP 128MB DDR
Leadtek GeForce4 Ti4600 128MB DDR
Leadtek GeForce3 Ti 500 64MB DDR
all cards worked in my sister's Pentum3 650Mhz on the EPoX EP-BX3 board setup, the system only has 3x 128MB PC-100 SDRAM LoL

Why I test this, just to see if even an AGP x8 card will work stable in AGP x2 mode as AGP x1 mode, well these all passed I'm quite sure the X1950 Pro AGP surely do fine

The there's the AthlonXP 2700+ with AGP x4

which isn't a problem for all cards.
Anyways to get back to the X1950 Pro AGP, I quite think that card will fit in nicely since it was exactly what was missing like a missing link idea. Can't wait to see one inaction even by this time of day an high End AGP card is always something great to experience with