While I generally agree with this statement (and would add "..has Visio" to your comment); unless you use many of the advanced features of Office/Sharepoint the Mac versions are quite capable of letting you integrate a Mac into a PC environment. I've done it and never had any issues with not being able to do what I needed, including connecting with our Exchange server.
Bonjour was a real gem - I could be at a client site, on their network and print when many of my PC based colleagues couldn't find a printer. Never could get the PC version of Bonjour to work right.
I also like how easy it is to attach external displays and show one thing on screen and another on the projected display. A PC can do that as well; I just OSX a more elegant solution. Win7 may be as good, I just haven't tried it.
In the end, a business computer needs to satisfy the business needs - for me, a Mac does the trick. YMMV
Dell support hell. My XPS has great support - but I paid for it. My other Dell boxes were a nightmare - CD Rom not working - reinstall Windows. Can't power up - reinstall Windows. Key fell off keyboard - reinstall Windows. Dell cut costs bu using outsourced script kiddy techs; most of whom were useless.
I really don't blame Dell - everyone wants the cheapest price and you get what you pay for. I wonder what percentage pay for a higher tier of support? Or will pay a premium like I did for an XPS to get better support?
When I say Dell 'support' I'm talking hardware wise, not software. When something breaks you don't have to travel far to get it fixed. Convenience, not necessarily quality was my point.
I've found Apple's support beyond being overly gracious, to be mostly useless. Anything beyond the simple requests get no where. Although there bottom level support is all English speaking and US based, they are little more than operators answering the phone.
If MS were to include syncing of SharePoint Lists and Document libraries to Outlook 2011 then they would cover 90 percent of users needs. The lack of syncing, as you say may be an 'advanced' feature. 2 years ago none of my customers were running SharePoint, now 100 percent do and its part of every installation we do.
Infopath would be nice but it'll never happen but I'd guess there must be some kind of XML form service that'll connect to SharePoint.
I can honestly say I've never had a Win7 BSOD on countless machines, then again I've never had a kernel panic on anything except my Hack Pro.
Both OS's are equal in robustness.
One area where osX is far superior is in battery management. There is something to be said for controlling the entire ecosystem. It is completely seamless the way it manages the battery.