I am new to linux also and set up a dual boot last month with Xubuntu 14.04 and XP. What I did was check the md5sum of the download ISO file (not the DVD) first. Now when you are booting from the live DVD, you can have it check for disc errors, it's worded something like that. Here's how to do that:
Normally, when you boot off that ubuntu disc, you will get a graphic of two options: try first or install. However, to check the disc, you do not want that. When the disc first *starts* to boot you will see a little graphic at the very bottom; when you see that immediately press your keyboard "space" bar. Now instead of getting that graphical 2 options, you will get a listed version. One option on that list will say something like "check for disc errors". You want to select that and see if it verifies that it is complete.
Note: Xubuntu uses the same installer so this should work for the regular Ubuntu you have.