My game crashes because of my "out of date video drivers"

[azzabob]

I have no idea if I am posting this in the right place because this is the first time I have ever been on the steam forum, anyway I got a new PC so I downloaded Portal 2 for it and when I click play a box comes up saying

Your video drivers appear to be out of date and could cause problems if you choose to continue and run the game we strongly recommend that you follow the link below...

Your Driver details
OS Version: windows vista (It says this although I am running windows 7)

Description: NVIDIA GeForce GTX 550 Ti

Version: 7:14:10:304

I clicked the link and it I downloaded the drivers and updated my drivers but it still is coming up with the message. Every time I launch the game it goes to the loading screen then crashes. My brother has the same Graphics card and it says and does the same thing.

This is the specs for my computer:
OS: windows 7
Processor: AMD FX(tm)-6100 aix-core processor 3.3GHz
RAM:8.00 GB
system type: 64-bit
Graphic card: NVIDIA GeForce GTX 550 Ti

I have no idea how to solve this problem and I have no idea who to ask so I came here hoping to find an answer.
Thank you for your time.