I have a similar situation at work, made worse by an archaic exchange server setup.
I have migrated my diary and to-do lists to an great app called "Informant" which allows me to synch google calendars, outlook and toodledo. You can download a free plugin that will allow outlook synch to google calendars. This way I have integrated diary & tasks on my iPhone and Ipad, and it is always up-to-date on all three devices. I have even been able to create private calendars that only synch to my phone and ipad. On the desktop PC I have outlook (which receives appoitnemts created anywhere) and a toodledo explorer window always runing. Its not seamless integration on the PC but it works, I don't use the tasks in outlook, I find them pretty useless.
I can enter, edit and access info anywhere on any device and get alarms on all devices.