I would recommend only using 4.0 for caps.

2.0 does caps at 720x480 dvd res, but for 
widescreen caps, it tries a larger res but messed 
up an introduces jagged lines into the cap.  
Needed to use hypersnap to get the widescreen 
caps.

3.0 tries to do caps at window size, but it 
messes up and introduces jagged lines for both 
normal and widescreen discs.  Needed to use 
hypersnap to get any cap.

4.0 is able to do caps at both the original dvd 
res and window size (with the correct viewing 
aspect ratio) without introducing jagged lines.  
Seems like they finally got it right.  Time to 
uninstall hypersnap.