Yikes, 889€, for the ds508, that's kind of expensive. I know you're paying for the raid5 performance, but how often are you going to notice the difference between 10MB/s and 30MB/s? Certainly not when you're on wireless, which for me is the main reason for needing networked storage at home. If I wanted to have a desktop, I'd leave the drives attached to it.

At work we have a terastation (Pro II, I think) which has worked just fine as a place to dump backups. At home I'm using an NSLU2, which has worked much better than I thought it would, it's perfect for streaming over SMB to the xbox media center.

I'm looking to buy something faster with more drives sooner than later, but I'm pretty cheap, and it takes a lot to justify the price of the $1k+ nas boxes.