Simple file downloading?

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C#

I wish to make a simple program in C# that, in a click of a button, downloads all files in a specified directory, to another specified directory (using text boxes, etc.)
I searched Google, but found nothing helpful. I don't want to open the files or to use FTP, I just want to download them (text files, pictures, etc.)

Also, which framework should I use? I use 2.0 (increasing compatibility, I guess) for most of my apps, but I'm relatively new to C# and want to know which of the .NETs will suit this app best (3.0 or 3.5 are the other choices...)

Thanks in advance.