ubuntu on macbook pro 2011 early

I have a macbook pro which I am going to put a new HD in soon and I have no install disks or anything. I was thinking is it possible to put ubuntu on it instead? https://help.ubuntu.com/community/MacBookPro

Also how would I do this? I currently have a mac air so I dont think I need another osx. any guides would be great as this will be the main os on the laptop

Make sure you have the right linux installation disk or img for USB stick 32/64. They are free to download and most machines can cope. If you like have search for Distrowatch website they have all the details and links of various Linux and BSD distribution. Simple method is the live DVD of Ubuntu download or via various Linux retail magazines. This way you can um and are if you don't like. Most use the Gnome or KDE
Desktop environment that are standard. but variety for weaker lower powered laptops use a lighter desktop.
Mac uses the BSD of Unix which mostly stable base to work from. Hope this helps