http://www.talkorigins.org/In fact I believe the earth is at least 7 million years old. Maybe older. I don't buy that it's billions of years old. Sorry, the evidence just doesn't convince me of that.
In there, you'll find sufficient evidence that the earth is **at least** 4 billion years old or older.
The uranium decay evidence is pretty overwhelming all by itself-- of course, you'll need a basic understanding of where uranium came from in the first place, how it got to earth, and what "half life" means.
Of course-- the continental drift evidence is overwhelming too-- identical species of fossils found in both Africa and South America pretty much proves those two shores were touching, once.
And at the current rate of separation? Puts it well beyond your "millions of years" figure.