I've got an Asus A7V133 with the Promise Ultra100 PDC20265 built-in. It does RAID 0 and 1 but it also works just fine as a standard ATA100 drive controller. It seems to have better performance than the default IDE controller, too, but I've not been able to find any authoritative benchmarks of how much better it is than standard ATA/IDE. Unfortunately, I've heard that WinXP can have issues with its SCSI drivers, so I am wondering if it's a good idea to use this as the 'default' controller for a WinXP system or if its safer to run from the standard IDE?

This controller will act as regular ide unless you have multiple drives configured as a raid, then you must use the promise drivers. No problems here Not adaptec, not DPT, not promise, I have two XP pro boxes with raid, and no problems at all