Not sure where you saw Darrel connecting RW to the PIC, in fact he says not to in this post.
http://www.picbasic.co.uk/forum/show...=2388#post2388

The R/W pin is exactly what it says Read/Write, with 0 being Write.

Do you have the contrast pin connected to a pot as recommended? That is the most common problem. That should be pin #3 on the display. Not sure why the data sheet does not so it. Got to have contrast control.