I take it you are talking about the PC version? In either case, the answer is no - you don't have to pay for them again. Bring Down the Sky is free for PC anyway, and if you are talking about Xbox, then all you need to do is download them again from XBL Marketplace (as long as you are reinstalling them under the same account).
If you got your PC version of Pinnacle Station from EA/Origin, you will need to have the Origin Client installed on your computer, and you can download and install it from there. BDtS can be a little more problematic for PC, so I will refer you to the following thread for the download and install instructions -
http://social.biowar...1/index/9618640In the future, when you are asking for technical help in the ME1 forums, you should specify what system you are using (PC or Xbox) and as much other information as possible - in your case, specifics about what exactly you mean by installing on a new drive. If Xbox, are you switching or transferring HDDs, or installing to an external drive? If PC, are you replacing your old HDD with a new one and clean installing everything, or are you adding a second drive?