Why Macs will never reign in business
1. PC's (the hardware platform) are cheaper. Way cheaper. There is no good return on buying the more expensive Apple Macs.
2. Microsoft has brilliant licensing deals setup, and they are here to stay. You know I can get Vista Business for $55 (upgrade mind you) and Office 2007 Enterprise for $25? It's insane. Apple won't license it's software (as such) because it could lead to cheap clones of their systems.
3. Almost all businesses have their structure based around a Windows platform (even if their server(s) is/are Linux-based, the clients are mostly - if not all - running Windows). The cost, to change over would be enormous.
4. MCP's are everywhere - in every field too. The closest actual Apple store is in Sydney (only a 20-something-hour drive from here). Where as there are two MCPs within ten minutes of where I'm writing this. Certified support is always at hand.
(Also, there are no Apple dealers where I am living either - the only place that sold them, Myer, recently stopped stocking them. They still sell iPods of course)
More to come if I can be bothered.

