There are also mods that address this kind of thing. But turning Pirates off is a good start,
Also talk to some of the modders in the forum, they can show you the ropes on tweaking
the game to get the Pirates where you want. And later if you want to get them closer to normal
or even more (haha, crazy idea now i know, but maybe something for later
)
Then once you know how to tweak the settings yourself, then you can bring them back up to
something which will give you a little more of a challenge, but yes, i do understand starting out
getting your head handed to you, it happened to me for a couple of weeks before i tweaked it
so i wasn't dying every game.
Just maybe one in three or four. 
Also you can ask for a modder (me perhaps this weekend i will have time) and they can perhaps
put something together to weaken or slow down the Pirates so it gives you a little breathing room.

What version of Sins are you running? Diplomacy or Entrenchment or the Original and the version
number if you have it. Its in the bottom right on the menu screen when you start up the game.
p.s Take a look at this, i forgot i already did this once! 
put the inner folders in the c:/users/appdata/local/ironclad games/sins of a solar empire/mods-diplomacy v1011 folder
(this is for windows 7, if you have xp or vista i think the line is:
c:/users/application data/local/ironclad games/sins of a solar empire/mods-diplomacy v1011 folder
(in the application data folder instead of the appdata folder)
https://forums.sinsofasolarempire.com/378900
Try the weak pirates first and see if it is too easy, if not enjoy, if it is, then bump up to moderate or to
strong, whichever you like, let me know if it helps, i would hate to loose a sins gamer just because the
pirates are a pain in diplomacy.
Take care,
-Teal