Help on dog nail clipping?!?

Okay so I am getting a 3 month old chihuahua and I want to know if I can trim the dogs nails with this nail trimmer since the nails are short>http://www.petsmart.com/product/index.jsp?productId=4188811&f=PAD%2FpsNotAvailInUS%2FNo Or would I have to use these?> http://www.petsmart.com/product/index.jsp?productId=4030486&f=PAD%2FpsNotAvailInUS%2FNo#RatingsDetail<br />
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And how often should I trim the nails ?<br />

You can buy a nail trimmer that you do yourself either at a walmart or a vet. Just make sure when clipping them dont clip where the nail is red underneath. That is where the dogs nerves are and will hurt him if u hit that. As long as you clip where its white then it wont hurt them