Monitor vs X servers

After installing Debian 2.0 on my 100MHz Pentium system and then
installing Netscape 4.52, I'm getting nowhere trying to figure out
if I can get a colour depth of 8 out of my current card/monitor
combination.

Montior is a 1990 Mitsubishi XC-1429C, with specs of:

Active display 240x180
dot pitch      .28
bandwidth      30 MHz
Hsync          31.5 KHz
Vsync          60-70 Hz
Max resolution 857x643

Video card is a Diamond Stealth 1MB DRAM, and strictly from
possibly impaired memory, an ISA card with S3 Trio VESA something-
or-other, probably new in 1996.

I'm guessing my limitations are in the monitor, but is there an X
server that will work with this setup to give me more than my current
color depth of 4?  The only server that would work when using XF86Setup
was VGA16, nothing else would produce any output.

A new monitor is not in the budget right now.  Any suggestions are
appreciated.

Thanks,
Michael
mjwatson@livenet.net