Lowes gone Mclaren in Downhill mode now.
Mclaren really need to sort out there management(which imo is Dennis and his anal attitude to everything)it seems to strain everyone who comes in, and create lack of motivation or frustration with the team and from my memory it has started with Hakkinen, then Newey and Hamilton which all seem to have the same reason for leaving allthough Hakkinen retired.
Although they wouldn't be able to get him till next year there best bet would be to get James Key even if thats a bit of a gamble, unless they pull a miricle and get Rory Byrne.
Magnesium heads do exist. I'd guess Tristan knows a lot more about this than I do, but I'd bet that even with thick linings of Aluminium, the Magnesium would be so prone to creep at F1 temperatures that it's just not an option. It just is too deformable when really hot.