Hardrive,
1) When you compare spec to spec a few Macs models cost slightly more, most cost the same or less than a comparable PC. As a general statement it's just plain incorrect.
http://www.linuxinsider.com/story/36120.html
2) Limited # of apps available. I've asked this before, give me one consumer retail software package that is either not available for a Mac or does not have comparable alternatives.
3) What support issues. It's common knowledge that Mac support costs are lower than PC's. Lack of support usually comes from close minded IT groups that don't take the time to understand what they are dismissing.
The rest of your issues deal with enterprise. Since that's a broad catagory it's hard to talk about but I'll give it a go.
General enduser, MSFT suite of Word Excell, etc.., not an issue.
MSFT exchange, Entourage supports Exchange servers so again not an issue.
Networking, Macs support AFP, SMB/CIFS, WebDAV and NFS file services running on Mac OS X Server, AppleShare, UNIX, Linux, Novell NetWare and Windows NT, 2000 and XP servers. We've got built in VPN with PPoE and IPSEC.
Printing, not an issue.
Anything more specific that I can address?
Scott