I do believe that SHIII only ran on xp/2000? When I first got it, I tried to install on windows Me and it refused.

personally I use 1gb of ram, machine still slow but I've got a cheap Motherboard.

Yup, Silent Hunter 3 only runs in W2K, XP and...debately...Vista. And for XP, 2GB is the 'sweet spot'. Having over 2GB of RAM in XP (32bit, Home or Pro) is for the most part useless, since pretty much all programs are compiled to run within a 2GB address space, thus making anything over 2GB useless. In fact, I cant think of any games offhand that will use anything over the 2GB memory address.

Possibly the best use of memory over 2GB is as a RAM drive....my laptop has 3GB RAM in it, I configure 1GB as a RAM drive (leaving XP with 2GB RAM), and install parts of the game into this RAMdrive. This has the effect of greatly speeding up load times, but makes very little difference in performance once in the game (ie: my GWX campaign savegames load in approx 30 secs).