Cisco VS Nortel

I am sure most companies are looking at or have implementing OCS, and are starting to integrate that into using the Phone system. Today our company has rolled out OCS world wide and started in integrate that using the phone systems. Today I?m currently use a Nortel BCMs system and I need to purchase another system CS1000 (CS1K)but another division of our company has started rolling out Cisco, my question is to the users of the Cisco Phone system users and Admins, how do you like them, Pro and CONS, I feel I might lose my beloved Nortel and have to go Cisco sadly. Anyone have a take on this. Cisco is a great infrastructure company and Nortel is a great Phone company.