Okay... so here's one for you. I have XP sp3 and my avast Icon is grainy and terrible. What gives?
Version 5.0545
I have XP Pro SP3 and mine isn't grainy.
The OS has virtually zero impact on the icon (unless you happen to have win2000), that is down to a) monitor, b) resolution, c) colour of the background, etc. etc. So I don't know which might have an impact on yours.
I have no problem with mine, see image, click to expand.