[Serusers] Presence and messaging: UA with SER

I want to be able to offer the following functionality (in addition to calling) to my users namely: notification when a user is on/offline, directory search, and chat. These simple requirements are met with ease by Skype. And yet there doesn't seem to be any combination of SER and a freely-available Windows user agent that offers this. I have been a little bit out of touch with this recently so things may have moved on since I last checked. The main problem seems to be on the UA side. I've tried (amongst others) X-Ten, SJPhone, PhoneGaim, Firefly, and Windows Messenger - none of them come close to Skype's ease of configuration and use. Am I missing something? Can anyone offer some suggestions about how to offer this functionality? Regards Cameron