I'm running XP on a 1.85Ghz AMD, 512Mb RAM; not a terrible computer by all means. I've never really had any problems with it before that I've not been able to sort out with a reasonable degree of competence.
Anyway, these days when I turn on my computer everything seems much slower than it did a few weeks ago, and the processor light is on for a lot longer at startup; if I open iTunes and try to play a song there are pauses and mass jerkiness. This happens at random intervals, I could be not doing anything and the computer seems to be struggling. I've checked for viruses and spyware, and got nothing.