I am also a total newbie, and the terminology is practically like learning Chinese to me. I had no idea what I needed or didn't need, but I spent some time doing some research. I didn't want to buy more bike than I needed, but I also didn't want to later feel like my bike isn't serving me to the degree that I need it to.

I decided that a carbon fork was going to be important to me since I wanted to minimize shock on long rides, but I also couldn't justify the price of a brand new 7.5 or 7.6. I think the carbon forks start on the 7.3's (but don't quote me on that) and the jump from a 7.2 to a 7.3 isn't too steep.

I liked the feel of the 7.5, and I kind of neurotically looked all over to find an older model 7.5 or 7.6 that fit in my budget. If you go to Trek's website, you can go to the "find a dealer" section. There might be a shop in your area that is selling a past season 7.5. I ended up ordering my bike from a shop out of state, but having it shipped to my LBS and assembled there. It was about 40% less than the 2011 model of the same bike. And FYI, as of March 1 (and in some shops, before then) Trek raised their prices mid-season for their bikes by 5%. If you're going to buy new, I would see if your LBS will knock at least 5% off to bring it down to last month's prices.

Cheers and good luck!