TrendMicro is an antivirus, antispyware program.. you can learn more by doing a Google search for Trend Micro
Your computer could be slow if the 40 GB hard drive is older than three years old (or sometimes two years old) and is made by Maxtor, Hitachi, Samsung, or Fujitsu... it could be starting to fail and they sometimes run very slowly before they fail altogether.
You can find out by going to the manufacturer's website and download their version of the hard drive fitness test and run it. It only takes a few minutes to run.
Also, if you have a lot of programs or processes running at the same time... which can sometimes happen with too many programs searching for evils, and other stuff going on, 512 MB might not be enough memory... especially if the memory is also being used by the video graphics or other installed hardware.
It would depend a lot on what is installed, and how you are connected, and other activities taking place.
CCleaner is a registry cleaning program. It is a good program, but will sometimes remove things that can make it run more slowly.
HiJack this is just taking inventory. When it is done, it is not adding to the workload.
These programs do not, to my knowledge, install themselves.