The BlackBerry Desktop Software is designed to be used with Microsoft Outlook, the default business solution for PIM data. There is no stand-alone calendar app or task/memo function in BlackBerry Desktop Software. The best way to get PIM data from one platform to another remains Outlook. Sync your Treo to Outlook, then sync the BlackBerry to it.
You should also know that BlackBerrys do not synchronize email. It gets sent to your device through a BlackBerry data plan, either BES or BIS. But then I'm sure, as an experienced user of PDA devices, you've done your research and already know this.