convert to PDF

I have several thousand ebooks in .txt and .doc
My nook simple reader only uses PDF

Anyway to easily convert the files?

Caliber can be used to convert from one format to another for e-readers.

To just make a PDF, install a PDF print driver. There are tons of them, try to find a free one that isn't annoying.

Yup, I second that. Calibre is good.