I've also got a Kindle for Christmas. I haven't bought any books for it, I
just download free/public domain ones and transfer via USB. I use Calibre
for ebook management - it converts between formats pretty well, so if PDF
isn't working so well for viewing you can convert it to a MOBI or whatever.
If the PDF is just a bunch of images, you could try converting them all to
TIFFs and viewing them that way - might work a bit better/faster.