I need to unzip a list of .Z files which will be kept in a folder using Visual Basic.NET.
For example, consider that there is a folder like C:\\FilesToBeUnzipped
How about SevenZipSharp?
It's a managed wrapper around the 7-Zip compression/decompression engine that is released under the LGPL. Although the code is written in C#, all of the functions provided by the library are fully accessible in your VB.NET code.
If you're a do-it-yourselfer, check out the 7-Zip SDK.
I see SharpZipLib and DotNetZip recommended a lot, but I am not sure if they support .Z archives.
I know that 7-Zip does, not to mention it's one of my favorite open source apps.