Lenovo ThinkPad X61 7767-01U 12.1-inch Tablet (1.6 GHz Intel Core 2 Duo L7500 Processor, 1 GB RAM, 120 GB Hard Drive, XP Pro) | Amazon price tracker / tracking, Amazon price history
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
X61, still a great writing/ second machine after all these years : r/ thinkpad
CMS 2GB (1X2GB) DDR2 5300 667MHZ NON ECC SODIMM Memory Ram Upgrade Compatible with Ibm Lenovo® Thinkpad X61 Notebook Ddr2 Pc5300 Sodimm - A38 System Specific Memory - Newegg.com
OFFTEK 2GB Replacement Memory RAM Upgrade for IBM-Lenovo ThinkPad X61 (7762-xxx) (DDR2-5300) Laptop Memory at Amazon.com
My X61 Thinkpad, which I use for school. T8100 CPU and 1.5 GB of RAM, running Ubuntu Mate 18.04. : r/thinkpad
Penryn beginning to pop up in Lenovo's X61 ThinkPads | Engadget
4GB 2X2GB Memory RAM for Lenovo ThinkPad X Series X61 (7674ES7) 200pin 667MHz PC2-5300 DDR2 SO-DIMM Black Diamond Memory Module Upgrade System Specific Memory - Newegg.com