Yeah Witcher is spot on....for around the same price you are going to pay for these you could get an HTPC that you wouldn't have to ask if it would be enough and any cheap gpu would power full 1080p/bluray...
Unfortunately what you are seeing as two cores is the atom hyperthreading. The msi wind i'm typing this on shows 2 cpus in sys mon and i guarantee it uses the old atom. But hey, as long as the performance is there, there's no reason to be bothered by it.
I can also fire up "System Monitor" and see two different cores running, kind of a strong hint that this machine sports a dual-core chip.
I'm testing this right now on the Asus Eee Box EB1012 which got similar specs and Atom N330 with ION/NVidia graphics. I tried running Ubuntu 9.10 release candidate 64 bit, seems to work fine. I see four processors,
that is; the two cores and each with hyperthreading. I'll find time this week to evaluate this further.