Sony Ericsson Xperia Arc ROM change
For sure! Hopefully there are professional ROM cookers at XDA-Developers that cook ROMs without any kind of bloatware. Here are some articles that I recommend you to check before flashing a new ROM:


Unlocking The Bootloader
Updating Firmware/Flashing ROMs
Optional: A Beginners Guide To Modding And Tweaking The Arc


After you done all that you are good to go flashing a clean ROM, my suggestions are:


[DEVELOPMENT] - CM7.0.3 - Free xperia project