If you used Vegas pro 8 that's more then enough.
You will find that editing is normally fine on a low spec machine, its the render that takes the power.
Capture follows the same procedure but there will be an option for HDV captures as opposed to SD.
Fire wire is fine and is the normal route to take, bear in mind there is no more data in HDV it is just compressed more to fit in the same space. The capture program will normally have FW as the capure option.