RAID 5 question

I have used RAID 0 on my last 2 machines and I love the speed advantage. My next machine will be RAID 5 capable and I will probably use it. Windows sees a RAID 0 array as a single drive with the capicity of both (all) drives. Since RAID 5 adds parity data doesn't that effectively reduce the storage space of the 3 drives? If so is it reduced by 1/3? Does Windows see 3 80 Gig drives as a 240 Gig drive or a 160 Gig drive?

You will have 160GB of usable space with Raid5.

Unless you spent a lot of money on a controller upwards of 200, I wouldn't go with raid 5 for the speed, unless you definately need the data protection that it provides. A three disk raid 5 will be noticabely slower than a 2 disk raid 0. Just back up your files to cd-r

I was going to ask about the speed too, thanks. I have to spec my bosses new Dell, and it's time for me to start building my next machine too. I can live with buying 2 Raptors instead of 3 and backing up with another drive.

My boss won't go for the additional tasks involved a back up drive. It would be fun though to place the order for 3 SCSI 320 15,000 Rpm drives and 3.6 Xenon!