It doesn't matter whether your ultimate goal is Castilian Spanish, Mexican Spanish, London Cockney English, Brazilian Portuguese or European Portuguese. When you are first learning a language, read reviews on the best resources you can find in the language (books, podcasts, audio cds, etc) and get those resources. Don't worry about dialectal differences or things like that at an early stage.
Yes, the differences between Brazillian and European Portuguese are much more pronounced than those between Latin American and Peninsular Spanish. However, I think that at an early stage in the language it is more important to focus on learning the grammar and how to communicate, rather than strictly adhering to resources from one region or another. That isn't to say that you should blindly mix tu and você or European expressoins with Brazilian expressions, just that you should focus more on learning the different verb forms than on the nitty-gritty details that you will undoubtedly learn as you deepen your knowledge of one variety over another.
I hope this advice is useful. Instead of strictly adhering to resources from a given dialect or variety that you wish to learn, I think that you should keep an open mind and simply use the *best* resources in a given language. I need to improve my European Portuguese but I'm having trouble finding the resources I need. So, I am going to buy a great Brazilian Portuguese grammar workbook and start going through it. I will take note of areas of difference between European and Brazilian Portuguese to the best of my ability, and in the future I will eliminate those areas of dialectal inconsistency. For now, however, I need to focus on the best resources I can find to learn the language -
whatever they may be.
One last thing (this is kind of off-topic). Here are two links to webpages that have helped me a lot in learning Portuguese. These webpages are basically just information centers that direct you to other pages/resources.
The second link is a Spanish website.
I look forward to hearing your feedback.