I use a P400 on an Asus P5WDG2-WS - works quite fineI dont want to spend more than £250 ($400), also do the hp p212/p410's work on non hp systems as I'v got a bog standard Asus with a i3.
With the old SCSI-RAID-Cards I had a lot of problems when used on consumer-boards whereas the P400 worked fine on different boards.
Just one thing about the P400: The write cache will be disabled when SATA-drives are used as a friend found out. (His test-setup was a P400 with HP Midline-Drives, a pair of 7.2k 500GB SATA and a pair of 7.2k 500GB SAS, so the same drives, just with different PCBs. According to him this also is mentioned in some service manual, for security and stability reasons... Ha ha...)
He is about to test if the P410 has the same restrictions rendering the controller quite useless for most of us...