Ok, I did one more run with the CPU FSB at 140 MHz, which surprisingly did not improve things much. It looks like the card is now the limiting factor. (The system is totally stable at 140 MHz FSB, at under full load running 46C, which is good enough.)
The bios reports my chip as an XP 2012+ now.

I think only newer drivers or additional FSB overclocking is going to raise the score any higher. (I don't plan on going above 140 though, the next step up on my system is 143 MHz.)
3DMARK2001 PROJECT FILE
PROJECT
Name My Benchmark
Description
Registration Name
Registration Key
3DMark Version 300
DISPLAY
Platform NVIDIA GeForce4 Ti 4200
CPU Optimization D3D Pure Hardware T&L
Width 1024
Height 768
Depth 32 bit
Z-Buffering 24 bit
Texture Format Compressed
Buffering Double
Refresh Rate 60 Hz
FSAA Mode None
OPTIONS
Show Title Screens No
Continuous Benchmark No
Benchmark Run Count 1
Demo Sounds Enabled Yes
Continuous Demo No
Game Sound Effects Enabled Yes
Game Music Enabled Yes
Game Detail Level Low
RESULTS
3DMark Score 10644
Game 1 - Car Chase - Low Detail 165.1 fps
Game 1 - Car Chase - High Detail 54.7 fps
Game 2 - Dragothic - Low Detail 185.9 fps
Game 2 - Dragothic - High Detail 109.8 fps
Game 3 - Lobby - Low Detail 141.2 fps
Game 3 - Lobby - High Detail 64.4 fps
Game 4 - Nature 57.2 fps
Fill Rate (Single-Texturing) 1030.2 MTexels/s
Fill Rate (Multi-Texturing) 2306.5 MTexels/s
High Polygon Count (1 Light) 50.1 MTriangles/s
High Polygon Count (8 Lights) 12.7 MTriangles/s
Environment Bump Mapping 151.8 fps
DOT3 Bump Mapping 159.1 fps
Vertex Shader 81.7 fps
Pixel Shader 123.4 fps
Advanced Pixel Shader 91.2 fps
Point Sprites 25.7 MSprites/s
SYSTEM INFO
System Info Version 2.2
Installation ID 0x00000000
OEM ID
CPU INFO
CENTRAL PROCESSING UNITS
Manufacturer AMD
Family AMD Athlon(TM) XP 1900+
Internal Clock 1.64 GHz
Internal Clock Maximum 1.64 GHz
External Clock 140 MHz
Socket Designation SOCKET A
Type Central
Upgrade
Capabilities MMX, CMov, RDTSC, 3DNow!, Extended 3DNow!, SSE
Version Model 6, Stepping 2
CPUID 0x00000662