do I really need to update service pack for hoster 4.0

[WDEWDAD7]

Ok.......................what is SP3, and how do you go about upgrading to it? I'm a musician, KJ/DJ. I am not the most qualified computer wiz......not at all, in fact. Sam said he held his breath when doing upgrades, I hold my breath, cross my fingers, cross my legs and toes, and...pray when I do them. Is SP3 listed as a Microsoft update????? Daryl.