Advice on a DIY Raid 5 Backup system for my Mac?

I got some old computer boxes laying around. If I pick up 5 hard drivers at $100 each, I can have 2.0TB in a Raid 5 configuration which is about double apples external wifi product and it's less expensive to replace a bad hard drive. If one hard drives goes, I just replace it for $100 instead of shelling out another $500 to replace Apple's external drive.

I've got some GNU/Linux skills and could set this up without too much effort.

Just wondering if there are any drawbacks to this roll your own solution and also want to make sure there's nothing that's going to prevent this from working.

TimeMachine, has a bug: cant create a image fine on a windows network file server. unsuported but works fine fix; search this forum. timemachine on wifi is great for backups.

a xp file sys will function too. consider raid 1. buy a seperate pci disk controller card todo the raid. a 3.5" drive uses 25watts.

if osx 10.6.x comes out may have zfs, this changes everything but till then anything will work.