NTOSKRNL.EXE is missing or corrupt

Iam from Portugal, sorry about my mystakes writing ...

After i install SP3 on my Windows XP PROFISSIONAL and after i check that i pc had a virus.

i install NOD32 to fix the virus ....
Find 10 erros to solved ...

After that i install spybot search and distroy them we find 81 entries ... we fiz them all ... after that 2 issues ... restart PC ...

Damn,

"Windows could not start because the following file is missing or corrupt:

<Windows root>\system32\ntoskrnl.exe.

Please re-install a copy of the above file."

i read a lot of pages in google, i did a lot of search ... and most of the problems or kind of the problems are solved with a CD of WINDOWS go to repair consulo do this, do that ... and its done.

I try already do that but after i press R appears a blue screen with a msg that said i dont have a HD and i could not go to recovery console ... the only option is F3 and start over again.

I have a 160G HD SAMSUNG SATA

i tryit to make a clean new installation on the same HD and the msg is the same when i want to start to install a new OS, u dont have HD ...

I already o to BIOS and i check that i have HD.

How can i put into this HD a clean copy of the ntoskrnl.exe ? ?

Using a BOOT CD with PMAGIC? or used another program to see what happend do my HD ? ?
or because of the missing ntoskrnl.exe my machine is assuming that i dont have HD.

i try already to put another HD in IDE and after install XP coud be able to see the other HD ... but i could only see the IDE HD...

Is is possible anyone helpme? i have a lot of information on that HD that can be deleted

Thks
Rgds