Hi,
On the Plot Settings tab on the Plot dialog box, you'll notice near the bottom-right there are 4 checkboxes, in a frame called Plot Options.
As default, the Plot with PlotStyles checkbox is checked. To Plot Object Lineweights, simply uncheck the Plot with Plot Styles box and the objct lineweights one will be enabled and checked. Trya plot preview to see if has worked and Hey Presto..
Don't bother using Scale Lineweights, unless you're using a non-standard paper or scale..
I hope this helps - Any more questions, let us know..
Cheers,
Renegade.. BULLET-PROOF DESiGNZ
renegade@tiscali.co.uk