Question regarding unlocked cell phones...

[sgtpepper]

So far in my experience with cell phones, I've always gone with the phones that are extremely marked down to around $20 with a 2 year contract. After getting extremely tired of having a crappy phone I figured I would save up some cash and buy exactly the kind of phone I want. My problem is that the phone I'm looking at (Sony Ericsson W810i) isn't offered under Sprint. Since I've never bought an unlocked phone, I don't know what kind of compatibility they have. So my question is, would a Sony Ericsson phone work with Sprint if it was already unlocked?