You could save some money
You could save some money going with an i3 instead of the i5, unless you have some specific use for the additional CPU abilities (ie. you plan to do a lot of transcoding, commercial skipping, etc.). The Sandy Bridge i3 chips… and even to some extent the Sandy Bridge Pentiums are more than capable of normal HTPC duties.
The SSD is definitely a luxury, but it is likely a luxury that you’ll like… a lot. You might look at some of the OCZ drives, unless you’re stuck on going with Intel. The Sandforce based Vertex II drives have worked out pretty well for me so far (I also had an Indilynx based Vertex drive that went belly up less than a year — it was replaced on warranty though and is still running fine).
You definitely do not need a 650w power supply. I’m running 350w Seasonics in a couple of HTPCs and a 400w fanless Seasonic in my main HTPC. All are still overkill.
When you take out the cost of the Ceton ($300 at newegg.com) you’re down to $700. Not that I’m suggesting not having the Ceton card… just that it is the most expensive component of the HTPC and makes comparing your cost for the HTPC against what “computers normally cost” difficult. You’d save about $100 going with an i3 so now you’re down to $600. The SSD is a $180 luxury, so now you’re down to $420… which is pretty low for a pretty nice PC.
Oh… you’ll need some RAM.