AVCHD is not an editing codec but an acquisition codec, which means that in order to be able to edit the footage, it will need to be converted/transcoded into a more suitable format.

Another bottleneck is that most AVCHD camcorders, record interlaced video, which is not suitable for computer/web use but only for televisions. Which means that if you plan to use your resulting video in computer screens, you'll need to de-interlace the video (preferably prior importing to editing software, but after the initial transcode). Canon released some camcorders which record in 1080p (progressive - no need for de-interlacing) format, but I don't think a lot of models support this function yet.

There are various workflows for these tasks, which they depend upon the available software you have.

My personal workflow from my 1080i60 Sony videos (already copied to hdd) to Final Cut is:

• Rewrap the AVCHD videos to a Quicktime compatible format using ClipWrap ($49). This process is really fast, because it won't alter the video files, just replace their container/headers.
• De-interlace the videos and transcode them to an editing codec (Apple Pro Res) using Jes Deinterlacer (free)
• Import them to FinalCut

For sure they will be other ways also to reach to the same result, but in order to help you more, please let us know of what software are you planning to use for editing your videos (I suppose iMovie will be your best choice).

Yes, I would recommend to convert it to a format that iMove can import. MKV is just a container format so you probably already have an iMovie-compatible inside that package. Under Snow Leopard just install Perian and open it in QuickTime X and then go to File->Save as ... and choose a suitable format from the dropdown menu.

If you need more control over your conversion, you could also convert it to an iMovie-compatible format using any of the video conversion tools available for the Mac. For a long time VisualHub was the king of video format conversion, unfortunately techspansion the company behind it, closed its virtual doors. There are two main open-source options derived from VisualHub, ReduxZero and TranscoderRedux they both should do the trick. Another option is Subler which will also convert to and from MKV video containers to an iMovie-compatible format.