NAS and Media Server

Hey guys,

I know there are a lot of people here with eyeballs on the computer bargains, so I'm hoping someone can make a recommendation for me.

I'm looking for a NAS and media server (preferably a single unit) for our home network. We currently have about eight computers (looking to add two more in the next few months), an XBox 360, PS3 and Wii all connected by ethernet or wireless to an Airport Extreme Base Station. It's a mixed Mac and Windows network (XP, Vista and 7 all in use), progressively moving towards an all-Mac network (though will still have windows machines for the next several years).

My dream list of features (in order of importance):

At least two HDD bays,
Gigabit Ethernet
Media server (iTunes, XBox, Playstation) - I think this is UPnP?
Bittorrent client
A usable GUI
RAID options (0, 1, JBOD)
Under $350 AUD
Easy enough for my parents to use (storing, retrieving and viewing media)
HDD hot swapping

I have already tried and returned the Netgear STORA. Though it appeared to tick all my boxes, the UI was atrocious and the transfer speeds were terrible. It also wouldn't play nice with Mac as advertised (randomly refused to copy files, with inexplicable error messages). The problems STORA had were supposedly fixed by Netgear with a firmware update, but that was so buggy they pulled it and for months it just hung in limbo - in the end I couldn't justify the cash I'd paid.

Looking at my feature list the only device I have found that checks all the boxes is a Drobo FS, which clocks in at over $900.