I'm not too sure about the pixel shader thing. I'm running a ATI X850 which is pretty dated now.
I haven't tried multiplayer yet, looks like it could be fun, but it's only on the tactical level of the game. Don't know about Hamachi.
THe demo only gives you a tactical level mission. It doesn't show any of the stratigic part of the game.
I've only had the game crash once. It was when I lost my first practice campaign. Being the campaign was over, I'm not sure if I missed anything.
THe beginning of the campaigns are kind of boring while your building up your forces and bases. You don't have the opportunities to get to go into the 3d tactical part of the game until war starts. That's when things starts getting fun.
I've had the game slow down one time when I had a large squadron of planes attacking a base with a large city nearby. But I did many other attacks since then and I haven't seen it slow down like that again. I think it was the city because when I looked the other way, things were smooth.
It runs pretty good for the most part on my 3.2 pent 4 and I'm enjoying it. I'm still figuring the game out to be honest though, so hopefully it will be even better once I get more comfortable with everything.
I'm not so sure I would want the same depth in the stratigic level for something to work with TOW. But some sort of dynamic campaign for TOW would really do it justice even if it was on a much smaller scale.