[Alienware x51 r2] Need to factory restore

Years back I have factory restored my alienware and since then I have: 

1. Lost the installation discs.
2. Deleted my recovery partition.

I do have a product ID key on the back, so is there a way I could do a fresh install of windows, put it on a harddrive, enter my product key, and boot it off that? 

I would not like to buy a new installation disc. 

Thanks in advanced

-Nick