The best thing you can do for the current generation of Paradox games, I believe, is make sure you have in your system a graphics card that has at least 1 GB RAM dedicated solely to the graphic card. I found I had problems running HoI3 with my older card (an integrated Nvidia 7300, at 512 MB) and once I got the new, self-standing graphics card (I got a Nvidia GT 220, requires only 400 W power supply) the difference was like night and day in terms of game speed and reaction to clicking the interface. The more dedicated memory on your graphics card, the more you main computer RAM can focus on calculating data for the game and not use its RAM for helping to support any graphical elements. 1 Gig RAM dedicated video cards have been around for a while now, and for mine I paid about US$100 or so IIRC back last autumn.