LCD monitors have been evolving really well over the years, and nowadays they have very good image quality and contrast ratio. They're also getting thinner and lighter, but I don't know if they're getting any better in terms of energy consumption.

About the Intel processors, I don't know much about it but I believe that i3, i5 and i7 are all from the same generation of processors, and they all belong to the most recent line of processors. The differences may be on the number of cores, size of cache, and things like that. If I had to guess I would say, i3 is the cheapest/lower performance, i5 is the middle price/middle performance, and i7 is the higher priced/higher performance.

About Windows 7, I haven't really tested it myself yet but everyone around me says it's quite good. It has a few new user interface things you have to get used to, and a few new features, but it should be easy to work with. Advertisements that I have seen say that it can stream video wireless from the computer to any TV... I know that's not true because TVs don't have wireless network connection built in yet that I know, so even if Windows 7 can do that, you still need a wireless receiver plugged in on the TV, and that probably isn't cheap. Anyway, all that is just to say that it should be a very good operating system, but don't think it will do miracles. lol