You'll find it somewhat difficult nowadays to find a laptop with Windows 7. The promotion of Windows 8 is rather aggressive. But they still can be found.
And you'll find it even more difficult to find a laptop with only 2 GB of RAM. If you don't mind if it has more (4 GB is common) that won't be a factor, however.
For spreadsheet, e-mail and Internet every laptop/notebook you buy new at the moment (but I don't mean things sold as 'netbook' or 'tablet') will suffice. So your main criteria are 15", Windows 7 and 'it has to come with a dock'. Now visit a few shops and ask for that. Once you have a longlist (or a shortlist) come back here with it.
What, by the way, would be your usage of a dock? At work I have a laptop I put in a locker every evening. Every morning I get it out of the locker, put it on the desk, connect (a) the adaptor, (b) Ethernet, (c) the monitor via VGA and (d) keyboard, mouse and VOIP-telephone via one unpowered USB-hub. That are 4 simple actions, that together take about as much time as the laptop needs to come out of hibernate. From then on the laptop just functions as a desktop. No need at all for a dock.
I am looking to buy a 15" laptop that has a docking station.
My goal is to use it as wireless in the house only and then use it with a docking station when desktop dies.
My needs are windows 7, 2 gb of memory. It will not be used for gaming.
Main uses are spreadsheets, e-mail, and internet.
Any help will be greatly appreciated.