Not a chance, unfortunately. The archives have to be generated by and into the MT database in order to be functional. Just copying them doesn't do that.

What you need to do is export your posts from your "old" Movable Type install, and then import them into the MuNu version. The export essentially just creates a text file that is formatted in a particular way that MT understands when it parses the file and sorts the content into the appropriate fields for the new blog.

There is an import/export button in the side menu of your "old" blog's main MT administration page. After clicking on that, the export information is at the bottom of the following page. When you tell it to export, it is going to give you a window with all your posts in it in plain text form, including comments. You're going to copy the entire contents of that window (CTRL+A to select, then CTRL+C to copy on Windows), then paste it into a plain text file (NOT Word!). Use Notepad if on Windows - just right-click on your desktop and select New -> Text Document. When you've pasted in the content, save it as import.txt

Once you have the export process finished, you'll need to upload the resulting import.txt file to MuNu. You can find the instructions in this post. (Just ignore the stuff about exporting from blogspot archives, you've already got your export file from the above procedure.)

Once you've finished the import, you'll need to rebuild your blog to see the results.

Going from MT blog to MT blog, there shouldn't be much cleanup needed afterward.

If you need more specifics, or would like a hand with the process, just let me know.

Paul