Do generic brand SD Micro cards F-up phones?

I have a Nokia 5310 and my phones manual says ALWAYS use 3rd party enhancements that are "approved" by Nokia and that includes memory cards as well but i've used so many other kinds of memory cards on my phone and have never actually had any problems with them at all...so if you want to you can use them as well and tha chances are very low if that can do anything on the phone as i've personnaly used the lowest quality china manufacturer memory cards on my phone without any probs.