SD Card Permissions Problems

hey everybody, i'm sorry if this has already been posted, but i couldn't find anything related to it in searches of forums, so i'm posting it now.

i'm running an ibook and mac os x 10.4.2. i have three SD cards both for my palm and my canon digital camera. for some reason, while using my generic SD card reader, i am now no longer able to write onto (or delete from) the disks; i can only read. when i "get info" for the disks, clicking on 'ownership & permissions" tells me that i can only read, and doesn't give me any options to change this. when i opened disk utility, i found that i also cannot erase the disks or repair/verify their permissions. what is going on and what can i do to fix it?

i'm the only person on my computer, so obviously i'm the admin. i'm the only person who's been using the cards, and i would really like to be able to edit them (meaning fix this problem) without having to delve into terminal or the root user, as i'm not very good with mac os x on the technical software side. i'd appreciate it if someone could get back to me on this before the weekend's over, as i'm hoping to be able to use them on tuesday.

thanks so much!