Reality is that on my commute for a few days after a fresh snow I'm likely to run into ice, loose snow, hard packed snow, loose snow on hard packed snow, loose snow on ice, slush, water and dry pavement.
Having different wheels or different tires doesn't help unless I want to get off my bike and change them every few feet.
Currently I'm using some inexpensive (cheap) Nashbar 1.95" tires that I believe are made by Kenda. The work fine for dry pavement (although heavy), ice and hard pack, suck for anything involving loose snow. My bike gets really squirrely. in even less than inch of loose snow.
Is there anything better for working in a wide variety of conditions? Would changing tire pressure help?