Hi Taxjew21,
I have both of the above mentioned. Here, IMO, is the problem with both: They both merely touch on the math. For me, I really needed a comprehensive explanation to math so I went with Manhattan's book series that also comes with 6 free CAT's.
I was worried about one of my scores and called Manhattan and spoke to a great guy named Taylor (their in house GRE expert) and he took the time to look at my practice tests and gave me sound advice.
I also, for 100 dollars signed up for Magoosh and it it WELL worth it.
I went a little crazy buying test prep books and these 2 are so superior that they are all that i use.
Hope this helps.