Well, is there some pieces of software I should remove before updating, I have heard of some errors surround packages that wernt unistalled befor updating?

If you are doing an update from 11.10 via update manager it "should" uninstall anything it doesn't need during the process. It will also disable third party repositories, such as MediBuntu, when the update process is initiated. If you are updating with a clean install nothing of the old system is left at all except if you have a separate /home and you choose to not format it.

Unless you actually give us more relevant information such as what you are updating from and how you are updating that is about the best answer I can give you.

Updating from 11.10. AMD64 No 3rd party repos, libdvdcss2 installed.

Isn't libdvdcss2 from MediBuntu?

In theory if you haven't got anything non Ubuntu (or more correctly Canonical) it should be ok. I have never really been a fan of updating to a new release via Update Manager. I did it and found I was better off saving settings and sources.lists etc and then doing a clean install.

In three years of using Ubuntu on a laptop and netbook, I did not have an online update fail on me.

Of course, I could have just been lucky.

I used the official method to install libdvdcss2, not Medibuntu, thinamabob.