First, forget Xvid if you are doing professional work. Aside from questionable compression, no one will be able to see the video without going through hoops and downloading codecs.
Second, you will not get the same quality export as your original image since you are going down in resolution, but it should remain relatively sharp.
Try exporting to Quicktime H.264 or WMV at a minimum of 2 Mb/s and see if things improve. If they do, you'll know compression is the issue and you can balance that vs quality.
Vince Becquiot
Kaptis Studios
San Francisco - Bay Area
