You could always try to look at the specific players latencys, so you don't get someone with a 3000 latency, which DOES LAG IN A BOOTYFUL BUNCH. But seriosuly, if it's PC lag, because of their specs, you don,t have much of a choice but to bear it all.
Helios-
It might simply be that depending on how big a fight you do, it's simply that no computer is able to process HUGE fights smoothly. I mean, I've seen similar pc specs, but with a much more advanced graphic card, and the FPS [U]STILL[/U]were kinda slow. And it may also depend on if you get really close into the game to see all the lasers shooting, ships blowing up, etc. Pcs nowadays aren't super-powered quite yet...
I'd personally say your specs are just about fine. The Processor is quite similar to mine, I have as much ram, and I'm also using Vista. Oh, and it runs just about perfectly on everything being at their highest quality. The only thing that I can suggest, is get yourself a decent graphic card, that's pretty much the only thing that'll really change the experience. Mine is an Nvidia 328mb graphic card, and it really makes the game run like a charm, unless you want to run an anti-virus
Don't forget lad, that's in single player, he's talking about, so I,d be surprised to see other players in that version of the game. Just to know, when the money disappears, is it all at once, or is it over a certain amount of time? Because it's happened to me too, before, but I discovered that when there are already pirates at the CPU's plants, then the bounty that you set is decreased, because of the ships the pirates are already destroying. Hope that helps! :D