Very Computer

I'm running RH 7.1 with AGP video card that has S3 Trio3D/2X chip and
8MB. Also I have a 2-button PS/2 mouse.
The problem is that I can't use all of the memory on my card. If I
choose 8Mb the X starts but the mouse looks like a white box 20x20
pixels. If I set it up to use only 4Mb then no problem occurs.?.
With this settings I can get only 1152x864 res. with 16 bpp. It is not
bad, but I guess I can get more with 8Mb video RAM...

Is there anyone that can help me?

Thanks,
Ivan