Also, if you open up your quest log with the map, and mouse-over the quest name, the location will be highlighted on the map. That may help you.
Oooh, it does! I never knew that... actually, you don't even have to open the quest log, just click on the quest title in your sidebar.
And, I hate to tell you guys this.... but Alderaan is one of the easier planets on which to find things... I have maps of all the planets on my guild site
, but they don't have quests marked...