2GB Memory RAM Upgrade for the Lenovo Thinkpad R61 Series, T60 Series, T61 Series, X60 Series and X61 Series Laptops (DDR2-667, PC2-5300, SODIMM) at Amazon.com
T61 - Wiki
Lenovo ThinkPad R61 15" Laptop Intel Core 2 Duo 4GB RAM 80GB HDD Windows 7 | eBay
Upgrading RAM in the ThinkPad R61 - YouTube
RAM memory for Lenovo ThinkPad R61
Lenovo ThinkPad R61i - RAM Replacement - YouTube
CMS 8GB (2X4GB) DDR2 5300 667MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with IBM Lenovo® Thinkpad T61, T61P Ddr2 Pc5300 Sodimm - B116