artcore01, there is a Ubisoft tool that scans your computer in order to give you a report whether your computer is compatible with the game. This tool is included on the Silent Hunter III cdrom. I might also be downloadable from the internet. Somewhere.
I just don't know if it is possible and allowed to send you this tool.
About the specs you give:
512 mb ram is a little low, but it should work. I also played with 512, and it works fine, except the loading time is very very long.
Your videocard is also more suitable for office apllications, but I think it will work ok with SH3, except for maybe the problem Maraz mentioned, don't know about that.
I really hope you get SH3 running on your laptop, because it is the best game I ever had. It's more like a hobby to me now. Didn't see that coming