Due to limitations in the OS....aka the 2 GB RAM limit just running highest graphics will crash your game. Unmodded Sins can run close to this limit just by itself. There been a few post around suggesting with a 64bit OS you can 'hack' the .exe and give Sins 3 GB. Make sure you have 4 GB min. if you do that. Ive not done it, not really had a problem.
I can run a 50-150 planet game with high settings. 9 AI and me, both with 3x the Fleet points with:
Intel Core 2 Duo @ 2.5 GHz
4 GB of RAM
NVIDIA GeForce 8600M GT
I will get lag end game with 4 or more end game fleets in the same grav well fighting. Or if alot of things go boom all at once. I have disabled alot of things though, to help my FPS and such so I can play like this. Turned off Show Trade Ship Icons, Show Ownership Icons, No Dust, No planet cities.
The biggest boost you can do IMHO, is trim your Empire tree down to nothing or the bare bones you need to use. For example, before I basically killed my Tree I had everything on autopin. Well with 50+ grav well the CPU needs to keep track of what in it, I would get horrible FPS/lag. So, while playing around with different options to reduce it, I found that little to no Empire tree got rid of most of my lag/FPS drop. This allowed me to crank up the Fleet points to what I have set now.
Anyhow, for what you want its not possible due to RAM limits for max settings. And any CPU now a days has its limits with either planet count or fleet size.
