Sometimes when I download a .rar File it Downloads but it wants to open with windows media center.. Why is this ? Help! thanks.
download winrar or a similar program if you don't already have one.
Download winrar like @maddoggy00 said or 7Zip (I prefer this one).
Afterwards, right click on the .rar file you're trying to open and click Open with... > Choose default program. Then navigate to where the unzipping program is installed. If you're installing 7Zip, it's under Program Files > 7Zip > 7zFM.exe.