QUESTIONS MSI FX5600 VTD256 DDR

Just found this group. Wish I did a long time ago.
The expertise in here is great. Thanks in advance to all of you
My system

MSI FX5600 VTD256 DDR video
MSI KT333 Ultra Mainboard AMI Bios
256mb Ram
AMD Athlon XP-1800 CPU clocked to 1533
Soundblaster Audigy Gamer 24 bit

My Questions

had lots of problems when i installed new card
deleted old drivers first and any reference in registry. then I tried a
few different versions and had major problems.
What is the best Driver for this card. I am presently using 43.45

My other questions relates to bios settings
Could someone please tell me what the optimum settings related to system
performance and video card performance should be.
Card is rated to 8x AGP Bios setting goes to 4x and what exactly does
8x and 4x mean.
I race online a lot F1 challenge and when i set bios to 4x agp my
framerate sucked
sso far vsync is off and FSAA is off in game and driver settings.

My old card was a gforce2 mx400 64mb so I am really eager to get the
full potential of my new card.
I realize there may be some other upgrades I need but so far this is
what i have so i need to get the most out of it

THanks