The fan/voltage/temperature monitoring worked out of the box with XP but the lm_sensors version in FC4 and FC5T1 did not detect the sensor chip.

An article in the January 2002 edition of Intel Developer Update Magazine left me thinking the chip in question might be either an Analog devices ADM1027 or a Standard Microsystems EMC61D101, but sensors-detect didn't seem to agree with me.

After digging out a torch and removing my glasses (there are benefits to being myopic) with a bit of squinting at the microscopic lettering I was able to see that the actual chip on the D945GTP motherboard is an ADT7476 which isn't directly supported by lm_sensors, however by a bit of judicious forcing of modules I was able to persuade it that an LM85 was close enough to work.

Contents of /etc/sensors.conf

chip "lm85c-*" "adm1027-*" "adt7463-*" "lm85-*" "lm85b-*"

# Voltage inputs
   label in0   "V1.5"      # AGP on Intel S845WD1-E
   label in1   "VCore"
   label in2   "V3.3"
   label in3   "V5"
   label in4   "V12"

# Temperature inputs
   label temp1  "CPU"
   label temp2  "Board"
   label temp3  "Remote"

# Fan inputs
   label fan1   "CPU Fan1"
   label fan2   "AUX Fan2"
   label fan3   "Front Fan3"
   label fan4   "Rear Fan4"

# PWM Outputs
   label pwm1   "CPU_PWM"
   label pwm2   "Fan2_PWM"
   label pwm3   "Fan3_PWM"

# Voltage and tacho scaling is done on-chip.  No 'compute' directive
# should be necessary.

# Set VRM version
   set vrm  10.1   # Pentium 4 LGA775

# Set voltage limits
   set in0_min  1.5 * 0.95
   set in0_max  1.5 * 1.05
#   set in1_min  vid * 0.95   # vid calculation seems wrong so use fixed range
#   set in1_max  vid * 1.05   # vid calculation seems wrong so use fixed range
   set in1_min  1.25 * 0.95
   set in1_max  1.388 * 1.05
   set in2_min  3.3 * 0.95
   set in2_max  3.3 * 1.05
   set in3_min  5.0 * 0.95
   set in3_max  5.0 * 1.05
   set in4_min   12 * 0.95
   set in4_max   12 * 1.05

# Set Fan limits
   set fan1_min 900
   ignore fan2       # AUX fan not on mATX variant 
   set fan3_min 0    # min speed of zero as fans can be stopped
   set fan4_min 0    # min speed of zero as fans can be stopped

# Set Temp Limits
   set temp1_min 10
   set temp1_max 65
   set temp2_min 10
   set temp2_max 45
   set temp3_min 10
   set temp3_max 45

Sensors output

[root@localhost ~]# sensors
lm85-i2c-0-2e
Adapter: SMBus I801 adapter at 3000
V1.5:       +1.55 V  (min =  +1.42 V, max =  +1.58 V)
VCore:      +1.35 V  (min =  +1.18 V, max =  +1.45 V)
V3.3:       +3.33 V  (min =  +3.13 V, max =  +3.47 V)
V5:         +5.05 V  (min =  +4.74 V, max =  +5.26 V)
V12:       +12.25 V  (min = +11.38 V, max = +12.62 V)
CPU Fan1:  1047 RPM  (min =  900 RPM)
Front Fan3:   0 RPM  (min =   -1 RPM)
Rear Fan4:    0 RPM  (min =   -1 RPM)
CPU:          +41°C  (low  =   +10°C, high =   +65°C)
Board:        +44°C  (low  =   +10°C, high =   +45°C)
Remote:       +42°C  (low  =   +10°C, high =   +45°C)
CPU_PWM:    51
Fan2_PWM:    0
Fan3_PWM:    0
vid:      +2.050 V  (VRM Version 10.1)