Peter
We used the following procedure:
Install a generic postscript driver, downloaded from adobe website.
Plot to file using the above printer driver. give the filename .ps extension.
Use (and download from the internet) Ghostview to open the file and convert the .ps file to jpg file where you can select a high resolution (300 or 600 dpi).
I know it's quit a hassle to get things done but it sure gives a very good result.
Luc