Um, did you try Googling "sync Sunbird cell phone", etc?
I'm a bit confused about your question. You mentioned iCal, but then mentioned syncing to a PC. As far as I know, iCal is only for Macs. So, you are looking for a combination of "iCal-like" software for a PC and something to sync it to a GSM cell phone?
Just Google it, and I think you will find a wide range of choices.