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
RAM memory for Lenovo ThinkPad X61
2GB (1x2GB) MEMORY RAM 4 IBM Lenovo ThinkPad X61s Series Notebook DDR2 A38 A38 | eBay
Lenovo ThinkPad X61 Tablet (7767) - full specs, details and review
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) - Walmart.com
OFFTEK 2GB Replacement Memory RAM Upgrade for IBM-Lenovo ThinkPad X61 (7762-xxx) (DDR2-5300) Laptop Memory at Amazon.com
X61, still a great writing/ second machine after all these years : r/ thinkpad
Upgrading the CPU in ThinkPad X61 — Wenting's Web Page