I haven't figured out how to take screen shots with XP. Think ya need some 3rd party (Party!?) software.
If your using 2000, then try this...
Okay, you are in a DOS Screen. Now what? Well, first I have to ask you this: Is your DOS Screen filling up your whole screen? The whole damned thing? If so, you are in (surprise) full-screen mode, and you cannot copy that picture to the clipboard. No you can't. So do this: Hold the Alt key in, and then press Enter. Yes, press Alt-Enter, and watch your DOS Screen become embedded in one of Windows' windows.
Is your DOS in a window? Great. If the opposite thing happened to you, and you find yourself in an all-DOS Screen, just press Alt-Enter again, and you'll be back to where you were.
Now, make sure your DOS-windows is the active window (by clicking it and making sure it is in the front of your sceen) and press Alt-PrtScr. That is, hold the Alt-key down, and then press the Print Screen key.
Now, go to your favourite painting program, and copy the clipboard into it (usually you can do this with Ctrl-C). If you do not have a favourite paint program, click Start -> Run, and type pbrush and then click enter. This will bring up the built-in, free Pain Brush program. Now, hold the Control (Ctrl) key in and press c, yup, that's Ctrl-C. And you've completed your first, free DOS Screen Capture!
If you don't want to include the window frame to your finished picture, you will have to edit it out with your paint program.