When booted up now, System Information reports:
OS XP Home SP3
M'f Eveshamvale
Model VIA_K7
System type X86-based PC (AMD 2400MHz)
Total physical memory 2048 MB (so yes it shows and MrMemory info indicates compatible)
Available physical 1.55GB
Total virtual 2.00GB
Available virtual 1.95GB
Page file space 2.60GB
System properties likewise reports at this stage:
AMD Athlon XP 2400+
2.00GHz, 2.00GB of RAM
Yet on other occasions (10 days after changing the RAM cards) it has reverted to reporting 512MB.... With no action e.g. to reseat cards. Hence the request