If I may jump in, I have done quite a bit of backpacking both for hunting adventures and non-hunting adventures. The Katadyn (used to be PUR) hiker water filter is a good one. I have used it all over MT, ID, WY, and UT. Packs up small and is pretty light. They make some pretty good chemical treatments these days that don't add unwanted flavor but I have not yet personally tried them. I keep some iodine tablets in my day pack "just-in-case".
I use a Marmot, synthetic 0 degree bag. I somehow always seem to get wet somehow when hunting/backpacking so I steer away from down. My bag is just under 4 pounds. I like the comfort it gives and I will sacrifice the weight for that. You have to make the call. Some guys go so ultra-light it is unbelievable but they definately comprimise some comfort. The synthetics just keep getting lighter and more compressible. The North Face, Marmot, Mountain Hardwear, all make great synthetic bags. As a side note, I am paranoid about popping an inflatable sleeping pad so I use a ridge rest and am thinking about upgrading to a newer closed foam pad made by the same company but I can't remember the name. The inflatable pads do tend to be more compressible and more comfortable, but like I said if you pop it you could be screwed and I have been with people who's pads didn't inflate. I was glad to have my cheap foam pad then!
A couple other things I have upgraded to over the years:
Titanium cookpot
MSR Pocket Rocket
Lightweight headlamps
All synthetic clothing
Eberlestock Blue Widow Pack
Todd, I applied for one of your favorite units. Not the one in the pictures above. It is a long shot but we will see.
Nathan