W98 – do we need these exe’s?

I’ve worked with low-spec PCs and have always “turned everything off” except EXPLORER, however, I have been informed by colleagues that I should leave SYSTRAY & TASKMON running – but no-one can give me a reason why. What do they do, and should they (or anything else) be running – what are the consequences ‘cos all my machines seem to have worked OK without them!