New PC

i just built a new PC but want to use old HD from the other one i got it all in but it will not boot win XP prof

i am at a loss how do i get it to boot up with out formatting?rolleyes

 

I believe you have to reformat the hard drive for it to work in a new computer, because the hardware and such are different.

 

Operating systems (XP, Vista etc) "bond" with your computer's motherboard and hardware when they are installed.
Therefore your HDD's copy of XP is trying to start using the old computer's hardware that is no longer there.
The only way I know to fix this problem is to do a repair install of XP on the HDD.
If you boot your computer from your XP installation disk; follow the promopts to where the computer gives you the option of installing a new copy of Windows or repair your current copy.
Choose repair. (Installing a new copy of Windows will format your HDD and you will lose any data you presently have on your harddrive.)
This will allow XP to find all the hardware on your new computer and "bond" with it.
You will have to download and reinstall any Windows updates from Microsoft after the repair.