What your customer sees on their monitor is different from what you and I see on ours. So the only way to have a perfect match is to get the pantone numbers and assign them again in xara to those squares. Even then you you can not verify that they are the same one as the pantone website (because the website is showing you colors in RGB). You need the booklet to get the numbers and see the colors on the booklet. How many pantone colors are there in the design? If more than 2, then it is best to do the whole thing in CMYK. Pantone printing is expensive.