You are very welcome, mate!
I am a great fan of having a "solid" game rather than a modsoup ending up with endless fiddeling (NEVER change a running system), so I do not try everything.
Your rig will handle everything you throw at it, regarding SH3.
Get the
4 GB patch first, it is essential for heavy modding, or have a look at the hsie / stiebler fixes (patches) and see what they do.
The new boats made by
Wise and
Wise and
Jeff-Groves (WIP) are incredible, just state of the art. Some are already available.
Start reading here, great info:
Click