Is the Western Digital My Passport Essential SE 1TB ok for dj mixing?

I was thinking of getting the Western Digital My Passport Essential SE 1TB to store all my multimedia and use it as a multimedia drive, such as running music and videos from the external hard drive with a multimedia program such as iTunes, dj program, etc. In better words, will there be any latency, etc?

That depends on a few things.  But just playing a song from the drive, there shouldn’t be any hangups.