yes... you CAN upgrade the processor, bought an intel dual core 2.0ghz , swapped my single core 2.16ghz and made a remarkable difference... i found the processor for less than $10 on ebay. (used) , and took to my handy work of disassembling. it took me roughly 1 hour, with a little experience in pc background. for a newbie. to carefully do this - 2.5 hours. and well worth the time invested to update a computer for a little more power.
What was the exact intel processor that you used for your build. I am looking at the maintenance guide provided by HP and there are a lot of processors on there with "for model 1.1 only," "model 1.2 only" or "models 1.1 and 1.2 only."
I am trying to upgrade from an Intel Celeron 900 to something with 2 cores in there. Any suggestions?