Yep, each day I add another piece of open source to my armory. I've been using the GIMP now for several months, its perfect for my needs. I'm not a graphic designer, so I usually just need something for resizing screenshots etc. I just wish it had grouped layers.
I use open office and of course joomla. In fact I've just downloaded Freespace2 an open source online multiplayer game

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Is Firefox open source? methinks it is, as is sunbird the excellent ical prog.
I reckon as commercial software becomes more bloated. Open source will become the defacto.
This may sound odd, but I think of all the major car companies. Their selling points tend to be interiors or inbuilt gps systems or playstations built into the seats. ie the developments in actual car design has long past reached its peak. Now car suppliers have to find other ways to make a profit.
Its why we have all these DRM problems with vista. Microsoft have succeeded in selling their OS to everyone, now they need other ways to rake in the cash.
Open source is different. Sure, the proggies still have a way to go. But in open source, bloat is simply unacceptable. Give it a few more years and commercial software (probably bespoke and niche) will be the alternative.
Open Source Alternative - Find Open Source Alternatives to commercial software