I have played around with a few Atom 330 systems and just can not get over the lack of performance...
Cpu alone isn't anything to call home about, but with gpu offloading is there ION really shines..
I'm not trying to sell ION as replacement for real desktop, but its perfectly suited for htpc (hulu, netflix, local and internet files playback)
Things ION does pretty bad: Video/Audio encoding/compressing, Games, heavy Apps like CAD and design software, but not of that is a concern with htpc.
Light Internet browsing and media - thats all...
I already posted small guide in htpc section, if you got more specific question on how to get/setup ion pc - post there