Try not to panic, its not called bird flu for nothing (ie, it only effects birds
)
Also, if it did mutate to a human form, it is unlikely to cause the widespread deaths that everyone is fearing.
If you think about it, the only thing that the HN51 strain wants to do, is to reproduce (like most living organisms/bacteria/humans/other mammals etc etc)and the only way it can do that it by finding itself a nice host to live off.
If it becomes so virulent (?sp) that it kills it's host off, then it runs the risk of being hostless, so to speak and so can't reproduce and so will eventually die out (which it doesn't want to do)
Anyway, what will probably happen, if (and that's a big IF)it does mutate to human form, is that it will hit quite hard to begin with (with possibly a fairly high percentage of deaths
), but then will gradually change it's behaviour so that it's hosts don't die (although may come ill), but remain alive and able to pass it on to another host.
Anyway, im just trying to be the voice of reason. My advis would be to spen less time reading the sun/mail/express/othr shite newspapers and buy yourself something worthwhile and rationale like the New Scientist (brilliant articles in there recently!) 
anyway, off now to stock up on bottled water and tins of soup, awaiting mass hysteria!