If you have to question yourself, then dont do either. Kids are far to precious to gamble on and realize its not something you wanted after all. I went from extremely selfish to extremely selfless when i had mine. Like clayton said, i felt the huge B slap of reality about 1 week after my son was born. Ever since, i have lived for my wife and kids and i would not change a single thing even for a second. The joy i get seeing my wife and kids together laughing and playing is better than anything i experienced before the 3 of them were ever apart of my life.
I feel i can speak for almost every man in the world that has kids and is married. There are things you are going to have to either cut back on, or give up when you decide to have a family. Some may be small, others not so much. But if and when you are truly ready, you will be willing to sacrifice them and still be happy.