With your system, you might first want to consider increasing to 512MB of RAM.  But before you do that, make sure that your system can accomodate more than 256MB.  You may already be maxed out!

I use a G-Force IV 64MB graphics card, and I am having great results...........

As horrible as it might sound, if you want to increase your fs2002 performance, you're probably going to wind up looking for a new system.  I used a Pentium III until last winter when I discovered it was a dinosaur compared to what was available!

I invested in a 2.4 Ghz Pentium IV.  My, what a difference.............

Good luck, and Happy Simming