So the PDF is correct (i.e. from what you can tell on screen), but printing it to your printer is not correct, is that right?

So in other words when viewing in Adobe/Acrobat Reader the colour appear dull, rather than bright green? (CMYK colours are always more dull of course).

By the way you can make the screen look (approximately) like hard copy CMYK colors in Xara just by selecting the Windows -> Show Printer Colors -> Simulate Print Colors.