it really is a very stupid question but the fact that you are aware of it says a lot about you (?????)
some of those .tmp files are files that are being used by running programs on the computer. If they are deleted, the program my lock up or in worst case scenarios, need to be re-installed.
PoolShark .tmp files are files used by programs or the operating system and if u delete them, nothing happens, if u try to delete them n u cant, cuz they're being used, nothing happens either, if a program is using a tmp file then u wont be able to delete so it's safe to just delete tmp files, although is not really necesary unless u see huge left over tmp files on ur hard disk n need the space