Contrary to popular belief, a vacuum just won't do the trick. It will push those needles down deeper into the carpet.
Instead, take a piece of duct tape (which has the strongest glue), wrap it inside out around your hand. Use the sticky side to pick up the needles. When the tape is full, turn it so that the other sticky side that was at the top of your hand is now at the palm. Pick up more needles. Keep doing this with as much tape as you need to pick up all the needles.
Go get one of those "Swivel Sweepers"! I just bought one for that exact purpose after watching the infomercial! It works fantastically, and is really great on carpet and all over the house. It sucked those pesky needless right up! Best of luck!