Upgraded the twins today. T420 got 16gb ram and a sled battery. 9cell + sled = 17hrs battery life. T480 got an extra 16gb of ram, up to 32gb. Happy with the
THINKPAD T420 RAM UPGRADE! (16GB) - YouTube
OFFTEK 16GB Replacement Memory RAM Upgrade for Dell PowerEdge T420 (DDR3-12800 - Reg) Server Memory/Workstation Memory at Amazon.com