Technically, no. But effectively, yeah, pretty much. Final Cut 6 can't cut AVCHD ? I don't think Final Cut 7 can either, if I remember right ? so it transcodes to ProRes during log-and-transfer. You won't enjoy cutting ProRes on such an old system.
You need an intel mac to transcode AVCHD to ProRes via Log and Transfer. There are ways to get the transcoding done (eg. Voltaic, Toast, etc..), and you would prefer using ProRes, but it's not going to be so much fun.