Ive never used one of those diagnostic cards before
In a way I dont see the point...unless it keep you from swapping out motherboards or something
I think just putting the money into some spare parts would be just as good of an investment
Spare
PSU
CPU for socket A and Socket 478 at least
RAM (pc100, PC133, DDR)
if a comp wont boot you strip out all the extra cards etc
see if its getting power (lights etc)
if not try the supply
if that doesnt do it try the CPU
if its not that then its probably the board, lol