Looking good on the specs front.
Whatever you've installed for SH3 then uninstall, remember to delete any SH3 entries in My Docs, and run a registry cleaner (I recommed CCleaner from Piriform - it's free and good!) to tidy up any messy entries.
Start your reinstallation of SH3 but NOT in Program Files folder of any sort (create your own is recommended - name it something like Gaming, or UbiGames...), don't install game shadow, don't click finish.
Appy patches (and I think the SF removal is here to), now finish. Reboot, and install mods (don't forget supermods must be installed over a fresh install) and play away...
...or so the theory goes
It is all stickied here somewhere! If I've got any steps wrong (as it's all from memory) I'm sure someone will say so.
Let us know how you get on