Display problems

I am running a HP Vectra (V1) Pentium 166 with 64MB RAM, with a HP D2832A Monitor (M500), the display adapter is S3 Trio 32/64 PCI (732/764). I am running Windows 98 SE. The problem is that at present I can only get 600X800 resolution at 16bits color. I have tried to find new drivers but to no avail, can you help me?