dont forget optical and coax audio leads for the ps3,and the sky,as you wont get surround from sky with hdmi.
so connect the ps3,with hdmi to the tv,same with skyHD,then connect the ps3's optical audio out,to the surround system,and the skyHD audio out,to the surround coax audio in(if your sky box has a coax audio out).
if it doesnt,you will need another optical lead,and one of these:
http://www.kenable.co.uk/product_inf...243928c10bd975
or these:
http://www.kenable.co.uk/product_inf...243928c10bd975
top one is a manual switch,bottom is an auto setup.
i would go for the top one,as you may want to connect the tv's optical out to the system as well.
so all in,you will need:
1 hdmi for the surround system - to tv.
1 hdmi for ps3
1 hdmi for sky(might come in the box).
1 optical for ps3
1 optical/coax audio lead for sky.
1 optical for tv- to surround system(possibly).
1 optical for switch-to connect to the surround.