Hang Yes!! Here at Freedom IT we use Linux and open source products as much as possible.
Our office productivity suite of choice is OpenOffice.org .
In accounts we use an Apple iMac G4 running OS X 10.4 that runs a derivative of OpenOffice.org called NeoOffice . This computer also runs our only piece of proprietary software: an accounting package called MYOB AccountEdge. I have heard of NZ companies running open-source accounting software very successfully, such as Quasar and LedgerSMB , but we have yet to trial these.
The CRM software we run is SugarCRM , community edition. This is a very powerful web-based customer relationship manager solution. It is free and open source software. We use this as our main calendar for work and potential work!
We have a Scalix email server running in a Centos 5.4 x86_64 KVM virtual guest on a Centos 5.4 x86_64 host server. The host server is also used to boot customer PC's via the PXE Network and run various tools such as hardware sniffers, disk cloning/management tools, flash updating tools, etc. There is also a Windows 2003 KVM virtual guest that we occasionally fire up.
We also have a Asterisk-based PBX server running Trixbox 2.6.2 on a(nother, real) Centos 5.3 i386 box! 
When you ring us you are going through a Trixbox Asterisk PABX. And, incidentally, the on-hold music you hear is available from the most excellent Jamendo website. Jamendo gives artists the opportunity to release their musical creations to the world. And they allow you to download it for free. You'll find some real gems! This is 'grassroots' music at its best.
We have another desktop PC that runs Fedora Core 11 with LTSP. This is used to run VMWare Server to provide access to a Windows XP virtual machine (amongst others - Centos 5, DOS, Windows 2003 Server). It can also be used to boot diskless thin clients to enable me to login to the Fedora 11 box.
There is also a Dell Latitude D600 laptop that runs Ubuntu Studio. It use to dual-boot Windows but it was wasted disk space! I never used Windows. So now I have virtualised the Windows for the odd occasions I need it! The laptop runs at a real nice 1400x1050 resolution. And I have even managed to get Compiz and wobbly windows running on it!
Finally the workshop does have an older Dell PC that runs Windows on real hardware for diagnosing customer problems who, unfortunately, still have to contend with Windows.
As an aside, we run a Fedora-based distro called MythDora that provides PVR functionailty using MythTV (v0.22) in our living room. We can record programs and then watch them when we like and one of the best parts is: it skips the commercials! We can also view the recorded programs from any computer in the house - Mac OSX has a MythTV Frontend , as does Windows (of sorts) and, of course, Linux!
Oh, and just a reminder, all the Linux-based stuff we use above IS FREE!
- Isn't freedom a wonderful feeling?!
