Lemme think what it takes to keep a brain alive without body....
You need the right temperature, correct resources, it has to be well protected, needs to 'float' in a kind of liquid, ect. (the nerves in your back are actualy part of your brain too) Besides, you won't be able to feel like you did before, also that technology isn't far at the moment. You won't be able to connect all the nerves, it's way too complicated and there are way too many to connect. A computer is easy and primitive compared to a brain. And how about loving someone as robot? And what if you want a child?
You won't get older anyway, most old poeple just lose their mind when they grow very old, 95 years and a clear mind is very, very rare. (Probably will even mess up faster in a robot) Your machine will need to get fixed too, a machine doesn't runs for decenia without it gets maintained. Also, where the power to run it will come from? A generator on your back? Even that won't make it. (nuclear reactors need cooling, forget about those too, exept if you want to be a whole ship or so)
Learning thing will take as much time too, you're brain isn't a high speed harddisk. You may notice that when you try to learn a lot and remeber it in just 1 day. And if you would try to store the data on a disk and acces it when you need it, you won't be able to use it to slove problems like you meet in mathematics, science or langues.
You won't gain strenght either, if you want to keep the same precision as your body has you won't even get the same strenght. Robots I did work with did look like they could pickup a car with ease, but those robots couldn't even bend a bar I could with my bare hands (and I'm not strong, really). I'm talking about robots that have more precision than a human hand btw. A crane has more power, but try to pickup a glass water with something like that.
The idea to be a war machine is outdated too. In wars like they run now you'll be a useless piece of old metal. Take irac, it's not like the "enemy" there is powerfull, or highly advanced. Still, the war isn't over there.
I think the idea could be used improve the interface to your pc (mouse,keyboard,screen,speakers), without cutting trough your nerves. It also is a great help for poeple who lost a leg or something simular. But to improve your life's quality as healthy person, it's no good, I rather would search biologic solutions for that. I would never want a other body anyway, I'm very happy with the one I have. And it's superior to anything they can make right now.
In short, nope, I wouldn't agree to life in a robot body
And dream on about the idea.
(sorry for my bad "english", I really should take course for it)
-Mel
