slow installation,slow boot,....

Hi there.....

My first topic (hello everybody)....not IT (learned some through the years..)..need your help
Bought used computer without HD (put new one in) and tried to install XP sp3 (previous OS: Vista home).Installation went very slow (7-10 hours) for couple times in last 4 days.My best shots were:
-reset CMOS (OEM board...nothing major to change in settings)...no changes (still slow)
-unplug all non-esential hardware.....still slow
-ran memtest: 1 pass in 1,5 hours...no errors
-put new memory moduls (2x1 gb),tried one in every slot.....nothing happend
-reload CPU (everything looks OK and sitting flat).....slow
-ran several test on hard drive,CPU,memory,MB.....no errors
-noticed:CPU usage very high,commit charge very low (7-9%) when running simply search in explorer (nothing in conection with installing windows)
-checked "DMA" and "PIO" settings..
My best guess: MB (faulty northbridge memory controller ) or CPU
To help you I ran CPU-Z and atached the results

This "thing" drives me nuts and you are my last hope before something get trashed
All the best