I have a XP Professional copy, P4 Prescott at 2.8 Ghz with Sp*. I downloaded and instaled.
I installed also the SP2 for two weeks.
I got the MSblast window ("you computer will be shout down ...etc) and i erased all
svchost.exe registry entry. My system crashed and i entered my XP professional SP* included
and i tried to reinstall the OS.
Here is the error messages:

" Setup failed to install the product catalogs. This is a fatal error. Error code is 426"
" The signature of Windows XP SP* Professional is invalid. The error code is 800b0*00"

I tried all the trick described in here and no result. The system make the same infinite loop.
The CD-ROm is the first boot option also i tried the "catroot2 to catold" trick.
I forgot to mention that i do not want to loose the OS, because all my registered programs and
all my work is there. Also i have the legit XP SP* copy with license.

Please help!