Emergency! Help needed.

Hello,
Ijust have my disk re-imaged, before that, I back up all the data filesfor SQL 2000, now I am trying to bring them back, however, I got errorsaying:
The file you specified is not a valid sql server database.

What I did is:
back up .mdf/ldf files
attach them after system is re-imaged.

The only change that might exist is: I applied SP4 after the new image. I might have an earlier version before the re-image.
Thank you.

I stopped the database. I copied all the database files. I did this numerous time.
I also just uninstalled SQL2005, 2000, and re-installed SQL2000, with the same patch sp3a.
I'm still getting the same error.
Crazy! What's going on?
Thank you very much.

What do you mean by 'stopped the database'?
Do you have '.bak' files or .mdf,.ldf with you?
Satya

I have all the mdf and ldf files. I saved the mdf/ldf files after I stopped SQL server. All the files were copied over to the same folder when trying to restore them.
I've opened a ticket with Microsoft. I'll post their solution here later on.
Thanks for help.

This is rediculous, MS doesn't have a solution to fix the problem. What they are thinking is the file is corrupted, but I burned not only database files, there are also thousands of files in other formats, only sql files not working now.
Does anyone have any recommendation?
Thanks lots.