Yes, you can. If you already own your own corporate domain (i.e. yourcompany.com or yourcompany.net), you can still use ScalIT. You will just have to modify your domain's MX records to point to the appropriate ScalIT mail server and web server. ScalIT will provide you with those settings. It is just that simple.
If you do not already have a corporate domain, ScalIT will help you acquire one, configure it, and manage it. The cost of obtaining a domain and keeping it renewed is included in the many services ScalIT provides.
ScalIT web applications are designed to work with most popular standards and protocols. This means that it should work equally well with OpenOffice.org as it does with Microsoft Office, with a Mac as well as with Windows, etc. Here are some popular and robust open source applications that are available for free download and usage:
Email and Calendaring
Thunderbird with the Lightning and Zindus Addons
Office Suite (Word Processing, Spreadsheet, etc.)
LibreOffice
Instant Message Software
Jitsi
Pidgin
ScalIT web applications also work well on there own, as web applications, and with popular commercial applications, such as Microsoft Office, Apple Mail, iCal, and iChat, and many others.