Depends on if you plan on editing HD video or standard def video.
If I'm editing standard def, I routinely use the "Uncompressed 10-bit 4:2:2" CODEC.
For HD, I've never edited in a lossless CODEC. I have recently used the "Apple ProRes 422 (HQ)" CODEC which looks great.
Here is a link to the Apple White Paper on the ProRes CODEC if you want to check it out:http://184.108.40.206/search?q=cache:_mSXcG1HpYgJ:images.apple.com/finalcutstudio/resources/white_papers/L342568A_ProRes_WP.pdf+apple+prores+422+hq&cd=1&hl=en&ct=clnk&gl=us
As far as compressing for final output, I prefer Compressor.
For web distribution, I prefer the H264 CODEC which is awesome.
If you need to convert WMV files on the mac, you can get a copy of Flip For Mac, which is a quicktime plugin for reading and converting WMV's to different formats. The WMV reader is free to download, but to convert WMV's to another format to edit with, you need the WMV Player Pro for $29
Once the plug in is installed, you can use any Quicktime application to read and transcode WMV'shttp://www.telestream.net/flip4mac-wmv/overview.htm