The open source community beat both Netgear and D-Link by years with the truly fantastic and very well polished XMBC (XBox Media Center). I can play content direct from my computer, from a disk in the XBox, or from the XBox hard drive. It play's every format I've ever tried on it and has a great user friendly interface. 

The biggest drawback is the XBox just isn't fast enough to play HD content properly, and you need a hacked XBox to run it on. I wish one of these manufacturers would build a hardware platform designed to run the XBMC software.

Netgear beat D-Link to this with the EVA8000 which plays a lot more formats including HD x264 without the need for transcoding, and also streams from a NAS as well as a PC shared drive.

Don't know much about the 330, but I have the DSM-320 at home and it's pretty good. Of course, it can't play HD files because of the machine's limited processing power, but it does fine with 'normal' divx and mpeg2. Sure you have to leave the computer on, but that's not a trouble, right ? No dvd burning anymore, it comes straight into the little box through wifi. If the 330 can do hd streams, it'll surely be worth its money.

Reviews of the EVA8000 seem to suggest that the device was released before the firmware was finished, just take a look at the reviews on Amazon UK for a flavour of the abuse it's receiving. I'm hoping D-Link can do better as I urgently need a replacement for the dead Pinnacle Showcentre sitting in my lounge.