Do you have hboot 2.02 or 2.10? If so, you may not be able to root using unrevoked right now. If you just bought your phone it may have either of those hboots. You can check by powering off your phone, then holding the power key and volume down key until it boots into recovery(?). Look at the second line, it will say "HBOOT- X.XX.XXXX", where the 'X's represent numbers. If it is 2.02.XXXX or 2.10.XXXX you won't be able to use unrevoked to root right now. But, there is at least one other method to root a phone with these two hboots at xda developers forums. Please search there.
If your hboot is lower than 2.02 unrevoked3 should work. That's what i used to root my EVO. Could you describe what's happening either on your pc or phone when you try to use revoked?