yeah, kind of like comparing apples and oranges....they're just different...for different needs.
if you need mobility, obviously a laptop is your only choice.
if you can afford top of the line, then maybe you could use a laptop as a desktop replacement.
if you are on a budget and need to not spend as much, you are going to get a lot more bang for your buck with a desktop.
i would have liked a laptop, but for the money i was spending i got a desktop instead because i could get a better system. however, i didn't really need the mobility factor. and, the easier upgradability is a plus.