As far as the .jpg is concerned why not just insert into Word, drag it to the size you want and save the document.
For the .pdf the only thing I can suggest ( and this depends on how many pages there are) is to take a screen shot of each page, use an image editor to crop to the area you want and insert as before. Alternatively print the whole document, scan each page into an OCR program and again save as a Word file. I have two progs that will convert a Word file to .pdf, but not the other way round I'm afraid.
Cancel the above. I've just noticed that version 6 of the Reader has a save as text option and I've just tried it. You lose all formatting and images, but at least you can get the text into Word.