I know that QNAP only supports VMWare on its more expensive Intel-based NAS'es. But I just read that Iomega supports it on its NAS'es that are relatively cheap. See
http://www.smallnetbuilder.com/nas/nas-reviews/30976-new-to-the-charts-iomega-ix2-200-storcenter-network-storage
...which links...
I am considering a QNAP TS-212 or TS-219P+. Is there a reason why these are not on your list? They do everything you describe, even your wishes. They are faster than everything you mention, more expandable and more feature rich.
http://qnap.com/pro_detail_feature.asp?p_id=192...
I am considering a QNAP TS-219P+ or Synology DS211(+) because they are both the best value for money in performance and features. As I concluded from the NAS Charts on SmallNetBuilder. I will be using it over a 802.11g network, which will be upgraded to a 802.11n network in the near future...
Synology claims the DS211 to be faster than the DS211j. If you are worried about performance, you should take a look at that one. Also see:
http://www.synology.com/enu/products/2bay_perf.php
You can also look at the QNAP TS-219P+ (mind the "+"!). But is is more expensive. And take a good...
I am looking for an affordable and usable NAS too, and came to the same conclusion: it should be the Synology DS211(+) or the QNAP TS-219P+. I think that choosing one of these will always be a good choice, because you already weeded out the mediocre ones (like LaCie 2big Network, WD MyBook World...