Some computers CAN'T be upgraded, I tried with one that was almost 10 years old but all I could upgrade was the RAM. I purchased a refurbished tower that came with optical mouse & a keyboard from e-bay for $99.
I would also suggest ordering a full antivirus system because all the free downloads for trials online DO NOT get all the bad things out of your PC. I ordered a 2010 Panda antivirus pro system from e-bay for $10, it is brand new & can cover up to 3 PC's for 1 year. When I got it I first ran it on my old PC (which previously had a free version of mcafee & advanced system care) it took almost 24 hours running that scan but it found 127 infections/viruses, 2 trackers, & a couple hundred spywares that the free downloads missed or just couldn't remove without upgrading, that alone sped up my old PC. I also ran the scan on my new pc BEFORE going online and found 5 viruses, 3 infections, 8 spyware & 1 tracker in it.
at 4:04 PM on Dec. 11, 2010