Actually, it's a re-make. Most of you weren't even born when the original "The 300 Spartans" came out, and it was my all-time favorite childhood movie (I saw it more than 10 times) because I liked the "Our arrows will block out the sun" exchange. It was a typical 60's epic movie with thousands of real people filling in as extras.
As far as historical accuracy is concerned, neither movie is what I would call even close to what actually happened, but then again, you should go to the movies expecting to see historical accuracy - let's face it, real history is almost always boring in a Hollywood film unless you add a completely fictional back-story to convince the audience to care about the characters and to establish who are the good guys and who are the bad guys.
I've got the original movie on DVD, and when 300 is released, I'll get that one, too. (I don't go to movie theaters any more.)