score:3
Yes it's fine to carry laptops in your carry-on bag. You can carry the external hard drives too, if you want.
Just be aware that your bag might still be gate checked. This happened to me back in October: Just as I was getting to the jetway they announced they were gate checking everyone else's bags because the plane was full, so I ended up pulling both of the laptops I was carrying out of the bag and carrying them onboard while the carry-on went under the plane (and on an unrelated note, actually ended up on a different flight but fortunately arrived at my destination before me). You could avoid this by carrying the laptops in a 'personal item' such as a small laptop bag or backpack that fits under the seat in front of you, but I wasn't expecting to need one of those on that flight so I didn't have one...
With respect to clearing customs in the US, it doesn't matter which bag they are in, as you will be briefly reunited with your checked bag between immigration and customs, and drop the checked bag off again after customs.