Opening .Dat?

well i have a runescape private server client and i need to open the main file cache.dat

i tried opening with notepad wordpad and editpad pro but all of them come out like this J%էI4+��^L���$���f�Ɩ$� �u
3jb����"���2-3ҭ��gG�V�KOj�������g᷐=�6h���s�.̧�������4
i need to know how to edit the main_file_cache.dat if its not to much trouble, i know that dats are made through many different programs and arent opened with a specific program, but if anyone knows any way to edit them, please help, many thanks
Answer #1
Try Orca….
Answer #2
i downloaded orca but it doesnt seem to support .dat file type
Answer #3
Of course Orca supports .dat files:

Answer #4
isnt .dat a mac file? maybe im just crazy…
Answer #5
well when i try to open the dat it give me the following error “Failed to open MSI database: C:\Users\Administrator\Desktop\Webbers Client\cache\.file_store_32\main_file_cache.dat
not sure what msi is >.<… and i guess dat could be a mac file but i know i got it for my vista and xp also