im not sure of specifics of the drives themselves to be able to say which is faster really, but, going by the specs in the links you gave... i would say to keep the OS/applications/games/videos all on the 250GB hdd (with backups made elsewhere if possible, to dvds/cds/external hdds, etc)... and put the 2*160GB hdds in raid 0 for your video editing, and for hosting your OS pagefile and internet cache as well (use the largest stripe size available when setting up the raid 0 array)... raid 0 is not recommended for storing essential data, but for temporary storage such as editing, it makes perfect sense, and youll see a performance increase above a single hdd, by up to about ~15%, when it comes to dealing with large files like you are
IMO this would be the ideal way to do things, if possible
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