Quick books? That's a software for SMB. It is not something big companies use. Read: SAP. Is there any SAP GUI client for Linux? Sure, it is. But it is officially supported for very limited set of OSes. Given the spectrum of Linux distributions, the choice is limited.
Second, SAP also has analytical tool, call it BI, BW or anything you like. Unfortunately, this tool only has a decent client based on... MS Excel! Do you want to use Linux? Good buy, BW and BEx Analyzer!
And, as for Exchange, there is a number of replacements...
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