Anyone know how to sex a cream legbar cross chick?

Hi,

saw some chicks for sale, that were hatched 25/07/08, they're not cheap at £7.50, but half the price of the hybrids they offer & soooo cuuuute!

They are unsexed, and have variying degrees of brown markings on them.  How do you tell what's what?

And does anyone know what "Silverlinks" are like as they had those too at £4 but they're newly hatched (30/07/08)?

Thanks