I think it will be difficult to have an open source video editing software currently available that is at par with Adobe Premiere Pro. For sound editing, may be you can try the freely available "Audacity", which I think runs on both Mac and PCs. IMHO, Adobe Premiere Pro is beginning to get better than Apple's Final Cut Pro for video editing. Premiere Pro is very tightly linked with Adobe After Effects, and the dynamic linking between the two is amazing, better, in my opinion, than Final Cut Pro's with Motion and/or Shake. After Effects API is very clean and easy to use than Apple's Quicktime for programming Final Cut Pro. I think Premiere Pro's API is a little messy, but still better than Apple's. I think the messy product in Adobe's arena is Photshop, which needs to update at many different levels.