I'll throw in my 2 cents too:
Shoes: I'm a big Salmomon fan. I've gone through several pairs of XA Pros over the years but am currently running in the new-this-year XA Pro 3D. These shoes supposedely have a lower center of gravity which translates into better stability and less turned ankles. I've done a presi traverse and 2 Pemi loops in them in the past 2 months and highly recommend them. On the down side the sole material is not as tough as the XA Pros. After only several runs, albeit long and rocky, they have significant wear on the soles. Another slight down side is the thinner soles. On a long rocky run, like the presi traverse where your running on sharp pointy rocks all day, you'll feel it by the end.
Socks: Smartwool all the way baby.
Ankels: I wear mechanically hinged ankle braces. Almost everybody I run into on the trail (both hikers and trail runners) ask me about them. I'm currently running in the McDavid brand
ULTRA ankle brace. After painfully spraining my ankles several times
I do not even think about trail running without them. To avoid chafing on my ankle, I wear the taller Smartwool Adrenaline 3/4 crew. I've wear my ankles braces all the time, including last year's Vermont 50, and never had chafing problems. I'm also happy to say that I've never turned an ankle either since I started wearing them last year.
Poles: Don't even think about it. I think poles are a hazard while running.
Pack: I'm in love with my new North Face Dogfish pack. It comes with a 2 liter hydration bag but I found I could stuff a 3 liter bag from an older CamelBack in no problem. This is essential on longer runs like the pemi loop. The materials are great. No extraneous straps bopping around. Just enough room to carry that extra wind breaker. There is even an emergency whistle built into the sternum strap.
Another very important item that newbies learn the hard way about is anti-chaffing stuff. I like BodyGlide and Hydropel. You MUST apply this everywhere you have skin rubbing together or on something (under arms, inner thighs, nipples, all over the unmentionables) or else you'll be sorry. You don't need it for short runs ( <10 miles) but it's a must on longer runs...especially when its hot and humid.
Hope this helps. Let me know if you have any more specific questions.
TOM