Sony Ericsson S710a

I'm sure this has been asked before, but I know that the phone only takes a 128 card. But I was wondering, if I put in a 256 or larger, will the entire card not work, or will only 128 of it work? I just picked up the phone today and I'm getting the card sometime this week, but I just wanted to make sure what would happen when I got it.

Thanks