Ok here goes, ive been trying for at least a week now to get SH3 to work on Vista.
After many attempts of installing nd uninstalling, the problems i was having was it would install the game, install the update but would not recognise it nor would it let me load GWX mod so with some help from the ppl on this site I am now able to use SH3 GWX fully. This is how I had to install mine.
ok start clean with SH3, remove all files associated to SH3 to either a disk or another hard drive pref external and one you can turn off so vista doesn't detect it with SH3 files. Before you load anything on you must right click everytime and run as Admin or it wont work or recognise any updates even tho it wil install them etc.
so:
(right click) load SH3
(right clcik) load 1.4b patch
(right click) load GWX mod
now right click on the new SH3 GWX shortcut and run as mod or it wont let you run it at all.
it will tell you to restart and this should be your first restart too.
Once it loads back up click on SH3 GWX shortcut and this time it should come up with drivers incompatable so here is where you load in Starforce and update its drivers, it will then ask to restart again.
Once it loads back up you should be good to go without any more right clicking and running as admin.
hope this helps as it worked for me.
