HOW TO

First of all, flashing your Samsung mobile phone can be pretty scary, but I assure you, you cannot ?kill? your phone. However, flashing your phone usually achieves nothing, as Samsung has a very bad habit of not fixing known bugs from version to version.
To find your version of firmware, type *#9999#? at the main screen of your mobile phone, as if you were dialing a phone number.

You will now see a software version information screen, look for a version sequence that may resemble this: ?E75UVWL2? The last two digits are usually what you look for, as they are the ?stepping? of the firmware version. They increment alphabetically, such that a D2 firmware version is newer than a B4, for instance

Connect Mobile Phone to PC:
Flashing a Samsung mobile REQUIRES a serial or USB data link cable. IrDA or Bluetooth WILL NOT WORK!! eBay is a great place to buy data cables, or from some of the fine establishments who have paid advertising on HoFo. I recommend an ?OEM? cable, as it is made by Samsung, and not by some third-party (non-OEM), as non-OEM cables may have questionable quality. All you need to do is to connect one end into your phone and the other end into your computer. If you have an OEM Samsung cable, you need to ensure that the switch on the side of your cable is set to D/L, not DATA, for flashing purposes. Please, when flashing your phone, make sure you battery has adequate strength to be powered on for 1-2 hours.
Backup Personal Data:

Using EasyGPRS, Samsung?s phonebook/PIM organizer tool for your PC, you can copy all your phonebook, SMS, organizer data, and multimedia to your computer easily. Download the latest version from a direct link on my website, or from Samsung?s website. You can backup your data either by using the import/export wizard, which can be a fuss to work with, or by just simply copying all data into the ?computer? category within the main screen. (Use the latest version of EasyGPRS to ensure compatibility with your firmware/model) Also, make sure you mobile phone is turned ON, and if you have an OEM Samsung cable, the little switch on the side may need to be set to ?DATA?. (not always the case, usually needed when backing up multimedia)

Do this by:

1) Click the category in which you want to backup(phonebook, SMS, schedule) and then click Phone MS or SIM in the lower left hand corner, depending on where the data is stored.

2) Hit CTRL+A on the main screen, where all the entries are listed, such that all entries turn a different shade of blue(they are all selected).

3) Hold down the CTRL key and click+drag on any one of the very small file icons that are next to the entries, and drag it to the computer listing in the lower left hand corner.

4) Left click on the computer, in the lower left, to ensure that the entries were copied.

5) Repeat as necessary for each category you need backed up.
Setup OPTIFLASH:

Setup OPTIFLASH by starting the program and hitting options->settings

Click the ?Generic? tab, and fill in your settings to match this picture, changing the drop down box for hardware platform to your phone.

Click ?COM Port? tab, and fill in the above settings. You may need to come back here later to try different COM ports (change COM1 to COM2?etc).

Click the ?Flash & Verify? tab and make sure all entries are blank.

FINALLY, fill in your ?Read? tab?s settings to match the above. You will come back to this screen later to pick where you will like to store your backup.
Backup Firmware:

It is recommended that you backup the f/w of your phone, in case you like your previous firmware version better, or your new version does not work on your phone.
First, go to the ?Read? tab (see above) and click browse to pick a place to put your backed up firmware file. It saves it as a .sre file. I recommend that your remove your SIM card before this step, just incase something goes haywire (doubtful, but it can?t hurt to be safe).

Now, from the main window, click the ?Read? button to begin! After a second, it will prompt you ?Power on mobile?. All you do is turn your phone on(if your phone is already on, turn if off then back on), and OPTIFLASH will activate. If it does not, check your COM Settings (see above). Now it will say ?reading flash? and may take up to 45 min to load your firmware into a file for backup. When it is done, it will say ?All is Well.? Now, unplug your phone and remove the battery for one second to pull your phone out of flashing mode.

NOTE: IF USING EXPERIMENTAL FIRMWARE (SUCH AS A FW NOT MEANT FOR YOUR PHONE MODEL) DO A ?FULL BACKUP?
To do this, do as above, but use 0x00000000 - 0x00ffffff as the range in the ?Read? tab of the settings.

Flashing your phone:

Most firmwares are around 50MB, but are compressed into a .rar file so that they are around 10MB. A .rar file is a compressed file such as .zip that can be opened with WinRAR (www.rarlab.com). As above, I recommend that you have your SIM card out of your phone, and a charged battery in your phone (or your charger plugged into the data cable, if you own the OEM cable). This process SHOULD NOT remove your pictures and ringtones, but this is not guaranteed (back up the pictures you have taken with EasyGPRS).
To flash:
From the main screen, click File, then Open. Now, browse to your .s3 or .sre file that you have downloaded and extracted from a .rar or .zip, and hit the OK button. You will now be back at the main OPTIFLASH screen. Click ?Flash? to begin the process. As above, OPTIFLASH will tell you to power on your phone, so do so. Now OPTIFLASH will do its thing, so give it around 20-40min and it will complete. Now, unplug your phone and remove the battery for one second to pull your phone out of ?flashing mode.? Power it back on and perform the following resets:

*2767*JAVA# Java Reset and (Deletes all Java Midlets)
*2767*MEDIA# Reset Media (Deletes All Sounds and Pics)
*2767*WAP# Wap Reset
*2767*CUST# Reset Custom EEPR0M

These resets do not NEED to be done, but it is helpful, as you may have another owner?s settings, picture, midlets, and WAP settings on your mobile now. At least do the last reset (custom EEPROM), as it may make your phone unstable by having another firmware?s settings on this running firmware.