Both are great games. Honestly, you are going to be happy regardless of which one you choose. Both look great. Both play well. So in the end it's all about which one has prettier cover art in your eye.
Thanks for all the input. I ended up picking up NFS: carbon. SInce i've never played any of the other need for speeds, everything would be new to me. Also, the guy at gamestop told me if i've never played ridge racer before, i probably wouldn't like it and it is alot different than normal racing games (with weird drifting and things like that).