Windows 7: Is this legitimate?

I tried logging into Gmail the other day, I keep getting this message. I have emailed Google about this but I have got no reply so far, I don't really want to give out my personal information online.

Getting an email to verify from Google is not unusual. BUT, you must make sure the URL is from Google. In your screen capture, it does have a Google URL. It's legit.

How it works : Verifying Your Google Account - Accounts Help

It looks to be legit but as the message suggest your account may have been accessed by another person

Do note I had to do this and its to reduce spam accounts, that's why they do it
Gmail account Mobile number verification

Looks legit to me.
Key is in the https://www.google.com/, and the padlock in the BRight corner.

Have you done any unusual activities recently? Such as send more mail in a week than your average?
It happened a few months ago with my paypal account. Been dormant for over a year, then I made a single US$25 payment to somewhere and I got this same message (from paypal, of course) I had to reauthenticate twice to release the payment.

Noticed your browser is Firefox.

Give the "FlagFox" add-on a try. Once installed it will display the flag of the country where the server is located in the address bar. Then, when you right click on the flag, you can select the "Whois" option from the pulldown menu.

Another page/tab will open showing you very useful information about the link in question.

The information may help you determine the validity of the Google link.

Just another way that Firefox add-ons help clarify mysterious things on the web.

Well I ended up getting in contact with google and the funny thing was, they gave me a link witch I had already tried and this time it came up with something different :S anyway I can access my email now .