That's one reason I ditched norton. Back when I used it, the dang thing wouldn't install. It did the same thing yours did and I was installing from a CD. I got rid of it because the install and uninstall were such a hassle, but the real topper is that it used so much memory and didn't detect stuff real well and updates were so huge(what the updates had or if they worked.... who knows?!). I prefer AVG for a free AV, it's free and light on memory and does a good job detecting stuff. For a paid antirvirus, I agree with what Steff said about NOD32. NOD32 is awesome but if you're like me and don't want to spend money on AV software then AVG will be fine.
Desktop: Dell Dimension E510, 2.5GB RAM, Intel P4 3.0GHZ, 250GB HDD, Windows Vista Premium. Might not be the best, but the old girl is still running good.