Good then. If you have already installed the jailbreak you should now move the "update_jailbreak_bridge_1.7.N_install.bin" to your Kindle root directory and install it via "Settings->Update Your Kindle". After that you can enable WLAN or manually download the 5.3.0 update and install it, the jailbreak should stay.
EDIT: Also you might want to consider installing ixtab's rescue pack
and then backing up
your partitions. If you need more information check my earlier posts in this thread.