Winter Clothing anyone??

So i figure my trip to Korea will be on the winter time. Come to think about it, I wonder,how do i dress for winter? Friends told me it's harsh winter there. So, how thick is the jacket should i prepare? and what about the shoes? What type of shoes? The structure? The design? and as well,how about the backpack? Which one should be it for this trip? I'm preparing for this trip little by little. Last week I went to check out on the winter clothing and yes,came back empty-handed, because there's sooooo many options and choices that left me confused as to which should i buy! :O However i did felt pretty relieved after the sales-boy told me that they always have discount for the winter clothing except for the 20% discount which only offered at certain times to the quite expensive ones. Help me yah!?! :D Thanks in advance!

EDIT: 1 JULY 2012: CHECK OUT TRAVEL TIPS :ON WINTER CLOTHING,MY STORY