This is the crucial point. For the performance specs, the X51 is somewhat overpriced, even if you take into the account usual cut of a distributor. However, given it's form factor (it's basically the size of a game console), it's actually amazingly priced.
Agreed. I would normally not consider purchasing a pre-made desktop, but this form factor does make it quite tempting. I would not feel ripped off, whereas historically I always felt Alienware machines were a little overpriced.
I spent about the price of the low end to upgrade my desktop to a AMD's current top 8-core... that doesn't include re-using my video card, case and hard drives. It's not a bad option at all. May actually get a couple of the lower end ones, as both my grandmothers are due for an update, and one of them needs to get away from windows (too much crapware gets installed).