[Wulfmann]

I have no problem running GW so must assume what Dell calls state of the art I call obsolete.
What card is in the Dell?
Also, RAM plays a big role in SH3 and in GW I suggest 2 GB DDR RAM for the harbors to run good.
Another thing to remember is what else you have running on your PC. I kept my old PC for email, photos, music files etc and run my 64 bit for my newer games so very little other crap that slows down games is running on it.
I am not trying to trash your system but I often hear people say they have it all goin on to find they are not running much.
A 256 VC does not mean much if the core is at 250 or the interface memory is 128 and it has 4 pipes. Another 256MB VC can have 16 pipes 600 core with 256MB interface memory and guess what, it runs much better. There is a difference in what is marketed as "State of the Art" and what really is.

That siad there are things you can do to help this. Open the SCR in mission editor (first make a back up copy). If you are like me you only use a few harbors to work from. You can look at those areas and either eliminate things or just move them somewhere away from your harbor to reduce the items slowing down the game.
You can redirect the bombers or reduce their numbers which will help a lot as their effects are taxing. Save it and try it out. With a back up ready to save you from any mistake you can tweak your harbors to suit your system.
I have my GW heavily modded as I like 90 percent but find many things lacking. That is my opinion and I have modded to suit that and not asked them to make everyone elses GW the way I think it should be.

Wulfmann