Im running a VP6 and this is what you have to do:
Make sure you have the latest bios (im running yt (its a beta but works great). you can get it from [url=www.vp6-board.com]www.vp6-board.com[/url]
then go into bios and make sure to Set MPS Spec. to 1.1 (its in advanced options i believe).
When you run winxp setup, when it says "press f6 for third party drivers" press f5, in a minute a little menu will come up and allow you to select what kind of computer you have, select "MPS Multiprocessor". DO NOT select ACPI Multi as WinXP will NOT work. This is a known problem on the VP6 that MS has yet to fix.
Now that your are running MPS multi with MPS spec 1.1, let xp install. Next, after you can log into it, go to device manager and view the properties on the raid controller. you should notice that the driver was provided by MS, not highpoint. You have to check update driver, select it from a list, and use the driver 1.0.3b (i think thats the right version, its the one that came with my mobo). If you dont force winxp to take the driver it won't. After you update it, check back the driver info to make sure it took. With this driver i have no problems in winxp
Ultrix.