Looking for a NAS

Currently I am using a linux based (ubuntu) server for NAS, Development (Jenkins, Nexus, Sonar, JBoss) etc. This machine is still consuming too much energy and therefore only on when needed.
But now I’m really starting to need a server thats always on. Mainly for Home Automation (e.g. http://openhab.org).

For my old server there are 4 hd. WD green 1TB. To keep the expenses small, I would like to reuse them. Therefore I was looking for a 4-bay NAS. The most famous are Synology and QNAP.

For now this machine looks really great:
The power consumption is still higher than I hoped (20W for the system + about 15W for the hds), but acceptable. The price (>400€) is also quite high. But hey its christmas 🙂