Thanks for all advice here.

And please believe me, I would never bite a hand that gives an opinion. Right now I bite fairly hard so you'd know if I did.
And... beyond all sense, reason and logic (perhaps), in the cold light of dawn (or a few hours thereafter) I will drag Sue kicking and screaming (not true) to the Apple Store in Meadowhall and buy a Macbook.
There are several reasons for this decision...
1) Life is too short (really) to carry on wondering whether or not to get one.
2) The cost is a tenth as much as Dave has already lost in depreciation on his car.
3) I have scrapped the idea of getting a 5D MkII, a 1Ds MkIII, an Audi RS8 and a villa in Cannes, so a Macbook seems fairly economical by comparison. (Note: Not all of these were actually possible.

)
4) What the heck!
So very shortly I could be transformed from a boring Linux nerd into a boring Mac nerd - watch this space if you're really desperate.
P.S. This message comes to you courtesy of a £250 Asus eee PC running Ubuntu-eee, so really I have no excuse for buying anything else.