I have been using Linux disks that I have received in magazines and now I want to get a 64 bit version of Xubuntu 12.10 (the magazine came with Xubuntu 12.04 32bit).

So making a disk should be this easy right?
Download .iso then burn it to a dvd. After that boot it into the computer using BIOS.

When I go to do this the drive starts to read the disk, then it stops.it does not work it just goes directly back to my old OS (Ubuntu 12.04). 

Am I doing something wrong?

I put the write speed at 2.4x which is the slowest my burner goes. I thought that would fix the issue, but no.