4GB Team High Performance Memory RAM Upgrade Single Stick For Lenovo ThinkPad T400 Series T410 Series Laptop. The Memory Kit comes with Life Time Warranty. at Amazon.com
Lenovo Laptop ThinkPad T400 Notebook - Core 2 Duo 2.40GHz - 4GB DDR3 - 160GB - DVDRW - Windows 7 Pro 64bit - Used with FREE 3 Year Warranty provided by CPS. - Walmart.com
Lenovo T400: How to upgrade the RAM - YouTube
Lenovo ThinkPad T400 (2765) - full specs, details and review
Memory for a Lenovo - ThinkPad T400 7417, 7420, 7425, 7434-xxx - Kingston Technology
8GB Kit (4GBx2) Upgrade for a Lenovo ThinkPad T400 Series System (DDR3 PC3-12800, Non-ECC, ) at Amazon.com
Used Lenovo ThinkPad T400 Notebook - Core 2 Duo 2.40GHz - 4GB DDR3 - 160GB - DVDRW - Windows 7 Pro 64bit - Walmart.com
Lenovo Thinkpad T Series T400 RAM Repair Guide | Installation Video