7zip help!

Hello, i'm having a really strange issue with 7zip. i have a 64bit os and i downloaded the 64bit version ( i have no idea if this info matters or not) but every time i download a file from the internet it opens in windows media center!! I HAVE NO IDEA WHAT TO DO! any help would be greatly appreciated! 

Is it specifically zip and 7z  files that are doing this? If it is you probably have media center set as the default program for those extensions. Assuming you're using Windows 7 or earlier (probably works Win8 but I don't know), try right clicking on the file and select Open With > Choose Default Program > Other Programs then select 7zip. Make sure the tick box for always use this program for selected file type.

You should also check your browser settings. Atleast Firefox has settings for different filetypes and what program to open them with. Options -> Applications.