i just got a Sony HVR-Z1U, so i need to upgrade from FCP4.5 to FCP5 to import HDV footage. my question is: is there a difference between FCP5 and FCP5.1? i thought i read it was $49 to upgrade from FCP5 to FCP5.1? do i need FCP5.1 to import HDV footage from my Z1U, or could i just stick with FCP5?

First of all you can't get FCP 5 or 5.1 new now, as the current version is 6. If you're looking at a used copy though FCP 5 will work with HDV, 5.1 is needed if you have an intel mac, but with the 5.1.4 version which was the latest before 6 came out you could use Motino filters and other FXPlug effects right inside FCP which is cool. So to answer your question specifically.... you could edit HDV with FCP 5, if you want to, but if you have a legit version of 4.5 then you could also upgrade right to Final Cut Studio 2 for the upgrade price, and get all the apps

What kind of Mac do you have? As Nate points out, if it's and Intel based machine you MUST use FCP 5.1.

I agree with his other points as well, at this stage of the game you might as well go all the way to FCP 6 unless you've found a really cheap copy of FCP 5. If buying used, also beware of copies which were used to upgrade to a new version. If you upgraded your copy of 5.0 to 5.1 or 6 then you cannot legally sell your old 5.0 software.