Intrigued by Arduino

First off, I have no experience whatsoever with microcontrollers. I do have considerable experience programming - however not for microcontrollers. However, I do really like to create things - and have possibly set up a target a bit unrealistic for a first project. It would seem simple, but I'm waiting for a little bit of input from some gurus.

Here we go: I would like to use arduino to monitor voltages somewhat specifically. For example, I need to know if a voltage(from an analog input) is approximately +- one of the following voltages: 1.782v, 2.242v, 2.960v, 3.630v, 4.310v, 4.660v, 5.000v. I have read a little about a "limitation"(perhaps not the right word) - arduino can read voltages between 0-5V and something about proportions. I was wondering if having 5v being one of voltages I need to monitor would be a problem as it is the upper limit of arduino? I have heard about voltage dividers and such, but I'm not sure how to implement one or if it is even necessary.

Second, I was wondering if there is a good site for idiots like myself to find material that an idiot can digest quickly. Perhaps one of you friendly people have a site that you use as a quick reference?

Thank you!

On the playground are a few links

Could I re-scale the voltage range as follows using a voltage divider. I think this would make the full scale of analogRead 0-1024 to be in the range 0V-6V. Can anyone verify this?

This was computed using the formula

Vout=(Vin*R2)/(R1+R2)

Vin
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#R1 20k ohms
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-------------------------->Vout to Arduino pin X
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R2 at 100k ohms
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_

Ground