Agree that the simplest is to click on the bar at the top of the "Type" column in WinExplorer to sort by filetype. This puts all files with the same extension together in the list, so you can Shift-Select them. Note that clicking the same bar again reverses the "sort-order" - which sometimes makes it easier to get to the type you want.

Clicking the "Name" bar will put things back in order by filename.

If files you want are scattered in several directories, the DOS xcopy command can be used to collect everything in one shot:

Note: you cannot copy more than about 250 files to the root directory of a:. If you make a directory on a:, the number of files is not limited.

In a DOS window:
Type a: and hit enter to go to the floppy drive.
Type MD NWC and hit enter to creat a directory named "NWC" on the floppy. You can replace "NWC" with whatever you like for a directory name, but in DOS it should not be more than 8 characters.
Type c: and hit enter to go back to the c: drive, or replace "C:" with the appropriate other hard drive destination.
Type cd\\ to go to the root directory of C: if you're not already there.
Type xcopy *.nwc/s a:\nwc and hit enter. All files with the .nwc extension in the root of C: will be copied to a:\nwc. All subdirectories of C: that contain a file with the .nwc extension will be copied, with the .nwc files they contain.

To see more about a DOS command, you can type the command followed by a "/?" as in "xcopy /?".
For long command descriptions that scroll off screen, add a ¦MORE on the end - XCOPY /?¦MORE - and the description will fill the screen and stop. Hitting any key will then show the next screen.
The ¦ is Shift-\, just above the Enter key on most PC keyboards - called a "brokenbar" or "pipe" symbol.

To find files of a given (nwc) extension that might be somewhere on a hard drive, the command DIR *.nwc/S can be used from the root directory. And you can use the "pipe-more" with it for long lists: DIR/S¦MORE will display one screen at a time. Hit any key for the next screen.

John