Ijust want to share my experience, i finally got my Arc S through Vodafone in Portugal, got home and went straight to rooting the device.
Locked Bootloader and firmware .62.
i've managed to reload a generic .42 ROM using wotan with free registration, got rid of the bloatware and the device was notoriously faster. but thats when things got complicated for me.
i've ran the expectedly simple to use DooMLoRD_v4_ROOT-zergRush-busybox-su.zip and it actually worked, i had it rooted, yay.
but at next reboot it was recognizing no SIM card anymore...
PS, i'm using x64 windows seven
fortunately enough, i've claimed it as a faulty device and got it replaced straight away. but now i'm relutant of trying to do it again, altough it is essential for enjoying such device... hope it all goes well for you. good luck