Trust what privateer says on this, Philipp.
Your motherboard and CPU are better than mine (Athlon XP 2400+ on an MSI KT4V) but my vid card is better and I have 2GB of PC 2700 (DDR333) RAM.
Adding an extra 1GB of memory would help you tremedously. SH3+GWX loads a bit faster and your system lags a lot less because Windows has enough memory that it doesn't need to keep swapping stuff around from the Virtual Memory on the hard drive.
Even with my ATI Radeon X1650 Pro 512MB video card, my system would still lag and take a long time to load stuff from SH3, until I upgraded my RAM. The more 3D objects and other effects you have to load into a scene in the game, the worse it gets.
It's not so much that SH3 is memory hog as it is WinXP. If you've noticed, having 1GB of RAM installed, Windows will use anywhere from 30-40% of it for itself and any background applications you have running, like antivirus, firewall, etc. It helps if you disable any Services you don't need and shut down any background programs you can do without.
So get that RAM, especially if you want to really enjoy that Lifeboat mod!
Then grab a better video card when you're able to afford one as it will allow you to use all the eye-candy your heart desires.
