Don't quote me on this but:

If you flash just the FIASCO(RX-51_2009SE_20.2010.36-2.002_PR_COMBINED_002_ARM.bin) or whatever it is referred to as, it'll upgrade the OS.
If you flash the EMMC(RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin) though, that should erase all your pictures/contacts/settings.


I'm pretty sure that your FIASCO install will kill all your installed programs though since I JUST did that. Make a backup of them if possible.
I tried to flash the EMMC but it wont let me. After my FIASCO install I booted back into Maemo after a failed EMMC install and I still had all my contacts/pictures but all my settings were gone.