ever since my last reply,i have changed 2 smps and then the sys stopped booting

.....gave my sys to 2 comp repair walas...they told mobo dead and repairing wud be temp only..so bought a new mobo(unfortunately the only 478 pin p4 mobo available in market was zebronics 845gv

)....and also bought a new 256 MB ram
then the old RAM refuses to make my sytstem boot

...so removed it
did a clean format and then installed XP SP2 but in the boot screen it just freezes

....tried several times with diff CDs...then installed win 2000 and XP w/o SPs....installed just fine but the sys is just freezing frequently....and then i have to reboot
seems that wheneevr i give my harddisk some work it freezes but not sure in this....
wht can i do for this ? may i sh8ud have bought a new one when the first symptoms of prob occured...now repair after repair occurs....