Tarantulas really get a bad reputation. They are not really aggressive and actually a very nice pet if you are not allergic to the hairs on the body and and you are gentle with them. The tarantuals are very fragile spiders and if dropped they can easily die from the impact.
The Tiger Rump may be the more aggressive of the two spiders. They have a more aggressive nature and that one you will need to be wary of. http://www.eightlegs.org/pag/pagan.html
Since I am not sure which one of the actual breeds you have, I will give you a sight about Tarantualas that will give you some extra information on the different breeds. Joan
The last site I gave you will give information on all the Tarantualas. Some of them go by a different name and it is easier to identify them from the picture. I would mostly with Herps, but have quite a few friends that not only keep reptiles, but also Taranulas and Scorpions. They love them and feel the aggression comes from the way they are handled. The slower moves are more reassuring and the Spider will get used to the handling and feeding tecniques of its owner. I have one frien that has raised rosey leg Tarantulas and the babies are the cutest little ones when just hatched. As with any pet I always warn the oner to get to know the pet before becoming to aggressive with the handling. Joan