Inspiron 17R N7010 new SSD installed, now I need Windows 7 OS installation disc.

Hi guys,

So my stock HDD on my Inspiron 17R N7010 completely *** out on me last week, so I bit the bullet and just bought I completely new SDD and installed it last night...now however, I need to install the OS again. Problem is, when I bought the laptop, Windows 7 came pre-installed, so I have no disc for it. How can I go about getting an installation disc and how much is it gonna cost so I can get my laptop up and running again? It's an outdated OS and the laptop is almost 6 years old, I can't imagine it costing that much. There's a Microsoft store right by me too, can I just go there and buy the Windows 7 OS disc you think?

Also, the original HDD was 640GB and this new SSD is 500GB, so the recovery disks I made when I first got the laptop are useless since Dell Datasafe Recovery (or whatever it's called) keeps telling me the harddrive needs at least 590GB of space (or something similar along that message). The smaller space on the SSD isn't going to be an issue with the laptop in general or when installing the Windows 7 OS is it?