PDF issues

I've made a document in Pages and saved it as a PDF (both by exporting and from the print options), and it's saved it exactly as I want it, no problems there. The problem is when I take it to a PC it opens up ok, but the layout is wrong, and it distorts some of the pictures in the document. I assumed that the idea of using PDF was that it's a standard across all platforms, but sadly it seems not to be the case.

Have any of you got any ideas why this is happening and how I might be able to get round it?

Just for the record I've had my Mac for almost a month, and I can't believe I didn't switch years ago!