There are pros and cons to using both online and offline calendar tools. When using an online calendar such as Google Calendar, you are reliant on having access to an internet connection and there not being a problem with the server. When using an offline calendar such as Outlook, it can only be accessed when you are at your computer, but it does offer additional features and is more easily backed up for security. In all likelihood, you use a combination of the two in a bid to get the best of both worlds. Here's five free Calendar related downloads that help to alleviate these problems and more.

Google Calendar Sync

Using Google Calendar Sync, as the name would suggest, you can synchronise the calendar you maintain online with the one in Outlook. Synchronisation can be one or two way so you can update either calendar and the changes will be reflected in the other. This means that when appointments are added to Outlook when at home or in the office, they can be synced to Google so they can be accessed from elsewhere, including your mobile phone.

SyncMyCal Free Outlook 2007 v2.7

SyncMyCal is a calendar synchronisation tool which can be used to synchronise data between Google Calendar and your Outlook calendar. Two way synchronisation means that either calendar can be used to create or delete appointments and the changes, additions and deletions will be reflected in the other.

Rainlendar Lite 2.8.1

Rainlendar is a highly configurable calendar application which holds upcoming events and urgent tasks, then alerts you in advance so you won't forget anything important.

The program can be set up to display your schedule in just about any way that you'd like. You might choose to view a single month in a calendar, a number of months, the whole year maybe - not a problem. And you can then display as many calendars in a window as you like. It's all very flexible.

Atchoo 0.71

Atchoo is a simple application that delivers desktop alerts for your Google Calendar events. Once you've entered your login details and the program has connected to your calendar, it will pop up a small window to let you know when some upcoming event is imminent.

Mozilla Lightning 1.0b5

Thunderbird is a great open-source and cross-platform email program including a newsgroup and RSS reader. It comes up short against the likes of Outlook, however, because of its lack of organisational tools such as a calendar or task list. Thankfully, Mozilla aims to rectify that oversight with Lightning, a Thunderbird extension adding these missing functions. And like Thunderbird, it's cross-platform, so works across Windows, Mac and Linux.