Did that computer come with CDs containing the original software, including Windows, that was installed on the computer? Have you ever formatted, i.e. erased, the hard drive and done a fresh installation of the original software, including Windows?
Do you have any spyware removal tools installed, and are you using them? Was the slowness a gradually worsening problem or did it happen rather sudden? If a sudden change, what happened just before the slowdown?
Where are you getting the "61.38 MB ram free" info? You mentioned games. What games are you talking about?
Do you ever run Disk Cleanup? Do you ever defragment the hard drive?