Bovingdon,
Surprised about your hardware config. Mine is similar, PIII 500MHz, but only 64K RAM, 8Mb video card and FS2000 runs fine??? The computer was new at Christmas though and has a very clean registry - can this partially be part of your woes???
Apparently there is a web site
www.outertech.com with a program called Cacheman which helps frame rates, etc.