If nothing is done about this then it can result in a small inaccuracy in the aspect ratio of the capture, i.e. if you only capture 2.30:1 and display it as 2.35:1 then the image will look slightly squashed.
The standard fix is to capture at a reduced horizontal resolution, e.g. 704 pixels, then add black borders 8 pixels wide either side to increase the image width up to the usual DVD-spec of 720 pixels. When displayed on a TV, these side borders are normally in the overscan part of the picture so are not noticeable. They can however be distracting if viewing on a PC.
If you are making an anamorphic version, then you have another option; capture at 720, but increase the vertical scale factor slightly to compensate for loss of the sides. By a quick calculation, I reckon the factor need to be increased from 1.33 to 1.36 (for a PAL capture, 327 vertical lines in the 4:3 source would normally increase to 436 after resizing to 16:9, but with the compensation it would be about 445).
So what's the vote? I am currently leaning towards the first option. Are side borders an issue to anyone? Would you prefer to see the full 720 pixels in use?