Don't really know anything about lotus notes. Where did you read that? I have always heard that exchange has the death grip on groupware in the enterprise. Either way they're out of my price range at home/SOHO.
The only thing Evolution is claiming to hookup to is Exchange and Lotus (now under Novell's wing), all of the others (open source ones) are web based.
If you can deal with the web interface (actually they're not bad, check out the demo's on their websites) you don't need to worry about a client install and of course you can allow it through the firewall and access it anywhere.
If you find a groupware other than Exchange and lotus that Evolution connects to I would love to know also.
SourceForge: As with any open source project it's all about meeting your needs, however I would start with the most popular. The popular one tend to have more support, better updates, etc.
For project MGT: do a search for customer relationship management on source forge too. SugerCRM is one I can think of off the top of my head.
http://www.sugarcrm.com/home/
Later,
M