I bought a cheap notebook in 2008 with an Intel Celeron processor. It served to my home-baked software development pet-projects during three years. Then I bought on E-bay for few dollars couple of Intel Dual Core CPUs to upgrade the notebook. I did not notice significant performance, but it warmed my heart with budged upgrade price.
This notebook serves now only as a Skype workstation, even though it straggles with its performance. Recently I found those CPUs in my drawer and made a little memorial to those CPUs efforts, with adding an Atmel Atmega 16 8-bit MCU (which I use in my DIY projects):