What is the best thing for preventing rust inside computer?

Could you tell me if this white thing is rust or something else:

http://home.drenik.net/orange/photo/rust/Set48_01.jpg (~50kb)

http://home.drenik.net/orange/photo/rust/Set48_02.jpg (~50kb)

http://home.drenik.net/orange/photo/rust/Set48_03.jpg (~50kb)

It turned red when I heated it with fan.
If you have any idea what it could be, please reply to: