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I dealt with the same question. Went for the Asrock ION 330 and XBMC in Ubuntu, which has great hardware acceleration (VDPAU). Plays everything I throw at it. No iTunes for Ubuntu however. Don't think other OS and media software give equally good hardware decoding. Open-source HTPC software on Mac sure doesn't. And iTunes itself is way too limited for use from the couch.

260 euro, all-in except for the HDMI cable. Dual-core atom, 2 gb ram, nvidia 9400m, 320 gb hard disk, cd/dvd burner, ultrasilent package. Can't beat that.
 
Can't speak for the dual-core Atom 330 and Ion, but I had a netbook with the Atom N270 and GMA950 and it sucked. I couldn't play Hulu/Fancast on standard def, let alone HD (and it played fine on my Macbook and iMac, so I know its NOT my connection). I won't touch another net-anything anytime soon. (Not that my PowerBook does any better job, though, lol)
 
Can't speak for the dual-core Atom 330 and Ion, but I had a netbook with the Atom N270 and GMA950 and it sucked. I couldn't play Hulu/Fancast on standard def, let alone HD (and it played fine on my Macbook and iMac, so I know its NOT my connection). I won't touch another net-anything anytime soon. (Not that my PowerBook does any better job, though, lol)

The ion is a an atom processor with nvidia 9400 graphics.

There would be no comparison with the c2d in the mb, but it doesn't sound like the op will need it. He will either have to do windows or see if the ion netbook he's wanting to get will support osx86.
 
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