Isaac wants the PC to bring him a GECK to study, and in exchange he'll give the PC his old power armor. However, no GECKs are available, but the PC can have Diana give him a holodisk with information about the GECKs which Isaac will accept as a trade.
Stealth Boy - A character with good Sneak and Steal skills (Sneak/Hard, Steal/Hard) can run off with the armor, but he'll need to find a way to crack the security code which has locked down the armor.
Charisma Boy - A character with a decent Barter (Barter/Average) will be able to persuade Isaac that everything has a price, and Isaac will suggest trading the armor for a GECK.