Yeah, that's what I did. I liked NBA 2K7 better last year but after playing all 3 demos from PSN, I decided to start out with NBA Live 08 this time around. I just picked up 2K8 yesterday though and will probably eventually get NBA 08 also.
If I could combine all 3, it would be the perfect b-ball game (graphics of NBA Live 08, gameplay/controls of 2K8, smoothness of 08).