Well it would be a good idea if the pdf's weren't coded to delete after about a year or so. That said I bought a Kindle 3g for my girl, and now its her most prized item. If you haven't already bought one, buy the 3g. It makes all the difference.
Got a Kindle2 for XMas. PDF are so, so on it. If you upload a PDF directly, more than likely it won't resize for the screen correctly, and most graphics won't be visible.
There is a convert process Amazon offers. Email the PDF as an attachment to <username>.free.kindle.com, put Convert as the subject and they will convert it so it reads better on your Kindle.
I would suggest MobiPocket Creator. It's a totally free program you can download and install. It will convert pretty much every .pdf into a workable ebook with pages and sizable text. It will retain most pictures as well. I like it better than the amazon converter. It's fast. I was able to convert "Unintended Consequences" in about 3 seconds and it's an EXTREMELY long book. Pictures intact. I use it to convert all my SHTF books from PDF to kindle-friendly formats. Just grab the .prc file after conversion and throw it on your kindle.