Hi, great forum but im still a bit confused

I am trying to upgrade my disk to a 09-1 but with no luck, i downloaded it and burnt it to a dual layer DVD but waiting 5 minutes to load it says some disk error

I have a I drive currently with an original 2005-2 Professional DVD

Firstly I cant tell which version o/s it runs to even try and upgrade that as it seems to be quite different to most ones stated here

Any suggestions/help would be much appreciated!

Cheers
Matt