checking your keyword rankings

what is the best place to do that to see how your rank for the keywords you want to rank for?

A very easy way is to download SEBooks rankchecker plugin for firefox

I would HIGHLY recommend getting Market Samurai. You can not only check your rankings, but also see the history of your rankings graphically.

A wonderful, wonderful, wonderful tool, and one of the TOP SEO tools of all times.

Disclaimer: I am not an owner of the company nor an affiliate, just a user.