The Celeron can certainly bitstream with no issue.
The Celeron buys you over three times the processing horsepower, six times with the lowest end Ivy i3. This comes in handy when you have a large XBMC library. When scrolling through my movies in my library, it takes seconds for it to pull the movie info, cover image, fanart, etc. Seconds is ridiculous, especially since my 2 year old pics the movie based on the cover art, not the name. It also allows you to open it up as a "real" HTPC instead of just a "XBMC streaming box". Running WMC on an Atom is just about pointless. I know, I've tried. It's just entirely to sluggish. Maybe you also want your HTPC to function as your home NAS. With a software RAID setup (be it ZFS, Windows, unRAID, etc) that is pretty much out of the question for a multi-tasking box. Crashplan loves memory and CPU cycles. Netflix HD, YouTube HD, Hulu? Slideshows for the most part. My fiance gave up on Farmville on the Atom the first time she tried doing it, within 10 minutes.
Don't get me wrong, if there is a great deal on a prebuilt machine I'm all about the TU. My beef is with Atom processors. They're significantly underpowered for most of today's usage, especially for current multimedia web usage. Checking email, solitaire and some word processing? Sure. But seriously, even low end laptops with AMD APU's (which are still more powerful than Atom's) can struggle on Facebook if you have more than a few tabs open. With things like the RaspberryPi available now, for a third of even this decent deal and it can do what most people are going to do with this machine, why bother with the Atom? At this point, it has a very niche market.
I liked my Atom when I got it, it's great for what I wanted it for originally, which was XBMC. But since then, I've wanted to do more. I want my library to load, quickly. I want to move all of my media disk's from my more power hungry 1st gen i7 workstation to a HTPC/NAS combo for some decent power savings. Now I'll actually be able to sleep or hibernate my workstation. I want to go to a full WMC setup with a cable card tuner so that I can finally get rid of my FIOS DVR's and worthless Tivo. Monthly fee savings alone will pay for my i3 box in 5 months. The i3 box will also serve as a distributed encoding client when I'm encoding BD to x264 on my i7 workstation.
An Atom box just can't do that and we're only talking a $30 savings, $55 if you want to get into a i3.
What are you using for your distributed encoding? Pm if youd like. Thanks.