For temps into the 20's (I've not had a chance to test this system, so I don't know how low I could actually go):

HH Explorer Asym
MacCat DeLuxe Tarp

JRB Nest as Underquilt
Homemade Gray Ghost as Underquilt
JRB Weathershield

20 degree Kelty mummy bag as quilt
CCF pad (if needed)

Clothing That I Would Wear
Polypro Long johns
Wool Socks
Grandma Hat
Fleece Pants and Sweater (if needed)