DivX5 generally looks better than XviD at low bitrates (below 1Mbit), but beyond that XviD is usually superior.
How long is the DV .MOV in seconds? 4.8MB sounds quite small, it's probably already encoded in Sorenson - this is Apple Quicktime's MPEG-4 implementation, and it's very good. To get it down to 1.5MB using DivX5 might look bad.
Also, if it's at a resolution of 640x480 or even higher, resize it down to quarter that (320x240) - that should get you down to 1.5MB or less with ease.
WMV is also an option - but only WMP9 and other WMP9 based players can decode it. Both DivX and XviD are usable in Linux and other players like Winamp.