If you have a good controller you will get the best performance with raid 0 on PCI/IDE, generally the ide controllers have 2 channels, drives have trouble transferring with more than 1 drive on each cable so RAID 5 isn't that great. If you have Sata/Pata, they may be less limmited, if the board has independant channels on each plug and each channel isn't sharing time on the sata/pata controller/can handle full duplex raid, and you have enough sata/pata channels to use 4 or more drives you can use RAID 5. You will have a big advantage over ide raid 0 with either pata/sata raid 0 or 5, if you are using huge video/audio files, you need LOTS of ram, I'd max out the board if it supports it, bus throughput is important, you don't want drives fighting for time to transfer over the same bus. A stand alone decoder processing card to relieve the CPU of the video/audio decode job would be a big help too. You will get best performance with RAID 5 through a duplex SCSI card, meaning one or more drives can be writing while one or more other drives are reading "where you get this???" I dunno, it's just some ideal situation that may not exhist... Large cluster sizes help speed things up when using large files.