...welcome back!
i have the SILENT HUNTER 3 'FOCUS' edition from AMAZON that does not have starforce on it. i now can play without the disc in my computer.
you can use GAMEBOOSTER or ALACRITYPC to help shut down background programmes. i personally used ALACRITYPC - I have a new pc now, with alacrity i was able to shut down nearly 100 background progs' which freed up loads in terms of cpu and memory on my old rig - which was similar to yours now.
with the mods, there are loads. i am at the moment on a laptop so i can not flag up my mod list. im sure others will be along soon with their help!
good luck and welcome back once again!
edit: after bacon butties and coffee + getting up!
my mod list, so far.
GWX - Captain America's Officer Icons
GWX - Lite Harbor Traffic
GWX - No Medals on Crew
GWX - Open Hatch Mod
Real Depth Charge
Rbs1_SH4_Effects_GWX_30_71
DBSM for SH3
Dowly's NeinHerrKaleu Mod
Extreme Wet Weather Gear Mod
Waterstream+Exhaust Combi V2.3 for GWX3
Flags_enlighten
Das Boot Clothes
GWX - 16km Atmosphere
Haunting Atlantic Wind
LifeBoats&Debris_v4
Hitman Optics for GWX3 v.1