if you want to have a poke arround
start with disk cleanup
then MLin's startup is easier to try out than sysinfo
http://mlin.net/StartupCPL.shtml
to see what starts up with windows
a good reference of what should be running is
http://sysinfo.org/
If you are getting regular crashes, bsods hangs etc .... it's probably best to backup your precious files (while you can) .... and re-format, re-install the machine.
things (old installs etc) inevitably pile up and it's a good idea to have a clearout - I do mine every 12 months or so