I just upgraded RAM in my aging nx8220 from 1 to 2 GiB with Kingston ValueRAM. Specs are: SO-DIMM, SDRAM-DDR2, 533 (PC2 – 4200). That helps a lot running Windows XP in Virtualbox which was kind of slow with only 512 KiB of assignable RAM. If you’re looking for HP’s Maintenance and Service Guide for the nx8220, grab it here.