Microsoft did that. Look how well their OS runs on low-end hardware.
I don't do client side programming anymore and I am _very_ happy with my Atom-based netbook for work. When I get home, I just hook it up to a giant monitor and happy I go.
And, BTW, Zope and Django run acceptably on it, so, I won't be seen migrating to a backbreaker notebook anytime soon.
I find OSX somewhat uncomfortable to use for me (a lot less than Windows - boy, why do people subject themselves to that?) mostly because it's Unix to a point and something completely alien beyond that. The problem for developers is the Unix half is very traditional 80's Unix and things have evolved a lot since that was cutting edge. I like my package manager to help me reassemble my box the way I want it to be and do so in servers in a repeatable way.
If your hacking is only around programming and reading Office documents and you don't touch system configuration at all, the Mac can be for you. If not, I would consider a vanilla PC with Linux as the superior choice.