Brickset is always a good point to start with. You also get a direct link to the Bricklink parts inventory.
The parts inventory is a great start to build a set, especially a Creator set. This way you can look for the needed bricks in LDD before you actually start building.
And don't forget the "Extended Mode" in LDD. Even with the many bricks in "LDD Mode" there are still some bricks that only exist as "red" bricks in "LDD Extended", especially the brand new ones.
Back to Bricklink: The Catalog is great, especially the cross reference between parts and sets: http://www.bricklink.com/catalog.asp
When you look for a part, you can also find the sets it has been used in. And once you've found a set, you can get a parts inventory with all the parts used in the set. Permalink
A good tool, if u want to buy parts for a digital (only LDD!!) moc, is the LDD Manager.
This tool is MS Access based and read out the LDD-File to tell u if u used parts that dont exist in this color.
After that it can copy the parts-list for Bricklink in xml format so u can instantly upload it as a wishlist in bricklink! :D