Best Way to Protect Harddrive Data?

[SOLAR]

I was wondering what is the most secure way to protect the data .ie. access to it on a windows xp box. Administrator passwords etc are useless simply because they can be overrided soo easily.

the next option of course would be encryption...However I want this machine to be a database server and I fear that encryption will prevent the database from being read. for eg. with pgp the file name is renamed with a .pg extension.

Does someone know of a package that will allow me to decrypt and encrypt on the fly. Also the feature of boot password and other security measures will be a plus for the package.

thank you for your help.