Toni,
For video, music and movies you cant go wrong with a Mac
Best to pop into the Apple Store in Perth and have a play
The new Macbooks have battery life for 7-8hrs
With software you can get Office for Mac 2011 and just use VMware, bootcamp for Windows OS if you need to run native Windows Apps
edit: Also consider looking at refurbished Macs as they are genuine Apple and come with full warranty. We bought our MBP from there in '08 and never had an issue with the laptop.
Link:
http://store.apple.com/au/browse/hom...mco=OTY2ODY2NQ