default program for opening compressed files

I was downloading various compressed files from the Internet. An automatic window popped up, listing all the programs I could use to open the files. In a crazy bit of experimentation, I clicked Microsoft Word and checked the box that said something like, "Always use this program to open files." Since then, I can't figure out how to change what program I use to open files (i.e. switch from Microsoft Word to WinZip). Believe me, if I can figure this out, I will never press the default option again!! Does anyone have any ideas?
Thanks!

 

Check out Bretts answer here. Just replace PDF with zip.
http://www.windowsbbs.com/showthread.php?s=&threadid=1701

Update. In a PM:

Thanks for referring me to the answer to my question. I had already done searches for zip and default but obviously didn't get the right keywords. Thanks again!

Glad it worked.