While painting around a vinyl window I saw that there is a 2x4 between the bottom of the window (the vinyl itself) and the drywall. It is half rotted out. How do I replace the wood and how much of the drywall do I need to cut out to do this? I am assuming that there are studs on either side of the window and that the window is secured to them so if I remove the rotten 2x4 under the window it will not come crashing down on me or the floor (bottom level of a trilevel, so the garden is right there). I am am thinking that I have to remove the casing (two sides and the bottom) and cut drywall and get the cats paw out. Since I have to replace some drywall would I be better off going beyond the studs so I can better support the new "footer" or is that overkill and I just need to toenail in the new piece.