The updates are mostly similar for any of the BDP models, but it is still strongly suggested that you visit the official site to have a look if anything is different for your specific model. Remember the article is only for the BDP-LX, BDP-320 and BDP-51FD players.
First download the firmware for your model at the site:
Pioneer: BDP Update
1) Extract the zip file and burn the ISO image file onto a CD-R or CD-RW. Any program will do. If you are unsure you can verify whether the disc has burnt successfully or simply re-insert it and “Browse" to see if the file is there.
2) Using the player’s front panels (not the remote), turn it on and open the disc tray to insert the disc you’ve just burnt. If the disc was burnt incorrectly the player won’t recognize it. Remember that you should have extracted the ISO from the zip file, not burnt the zip file directly.
3) Close the tray and the “Disc Download" message will appear. Leave the player until the “Download OK" message appears and the player ejects the disc. Remember not to touch anything until this happens, even if the player appears to be ejecting the disc before-hand. The update can take from 15 to 20 minutes.
4) Remove the disc. The unit will have gone into stand-by mode so switch it on and check the firmware to see if the update has completed successfully.
If you have problems check the update instructions on the site given above. They also give help in case a problem has occurred. The instructions are text files, and can be found by clicking on your BDP player model and looking underneath (the model information should be in red writing).