First off 46 miles rt is a long commute. Eat lots of oats and brown rice. Drink loads of water. Think and eat like an athlete, because at this length of a commute that's what one becomes. My commute's 41 rt w/nice wide shoulders most of the way. Brace yourself for harrassment in the form of honking, yelling, etc. You're going to need really good, flat resistant, long wearing tires. There are several brand/makes to choose from. You'll need good lights as well as reflective, hi-viz clothing.

Carry your belongings on a rack/bag set up, not a backpack. Most of all get a bike w/a compact double crankset and 9 sp cassette max. 10 sp chains are too light for load bearing. Don't get a triple crank set as they're more trouble than doubles. Triples are for off road and touring. Here's the bike I recommend: http://www.bikesdirect.com/products/..._cross_cx2.htm Or something similar. It's got braze-ons for a rack and is a very sturdy bike w/really good Alex 500 rims. The stock tires are too soft/slow for pavement and will flat within 2 weeks. Change them out asap. Also, get full coverage fenders for wet conditions...your drivetrain will thank you.

Btw, the top end of this bike is 29.9 mph @ 90 rpm. Plenty fast. Good luck and have fun.