WinZip used to be my compression program of choice way back when and was the first shareware program I ever bought. However, one piece of functionality in the Windows 7 Operating System, and in Windows Vista before it, eliminates the need for a separate archiving/compression program.
In order to create a compressed or zipped archive select the files and/or folders you want to compress and then right click. Go down to Send To and then click Compressed (zipped) folder.
Once you do that you will see a zipped folder ready for you to rename.
If you now click on the zipped folder you will see the inside of the archive as shown below.
You browse a compressed folder just as if it was another folder on your computer. If you click a file inside of that compressed folder then it will be opened in the files default program; if you delete it then it will be removed; you can also drag and drop files in and out of the compressed folder.
This is great for reducing the size of files you might want to send to someone by to reduce the size.