ThinkPad X61: The Subnotebook That Got a Second Chance - YouTube
Lenovo ThinkPad X61s (7666) - full specs, details and review
4GB 2X2GB RAM Memory for Lenovo ThinkPad X Series X60 ( Type 1706 ) Black Diamond Memory Module DDR2 SO-DIMM 200pin PC2-4200 533MHz Upgrade System Specific Memory - Newegg.com
A-Tech 8GB (2 x 4GB) RAM for Lenovo THINKPAD THINKPAD X61S | DDR2 800MHz SODIMM PC2-6400 200-Pin Non-ECC Memory Upgrade Kit at Amazon.com