Quadros? I didn't think we were talking Mac Pro (the only mac that accepts discrete cards) and I have no idea.
Indeed fat32/64 might be faster than NTFS hence the reason ext4 was created. Nonetheless what advantages do you see in NTFS over HFS+ for a desktop user?
And then you want to compare servers? I'm totally confused. Are we talking about a server for this guy? Personally I wouldn't (and don't) run anything but linux for a server. No version of OSX or windows is going to touch it for speed, usability, stability and cost so why would anyone care? But since you do, Snow Leopard made great leaps in server performance over leopard. Rewriting big chunks of the OS in Cocoa has that effect. Lion is likely even faster as Rosetta has been ditched.
You kinda forgot to quote all the stuff about faster boot times, etc.
Now back to the user experience, you have none with OSX, I have tons with all of the above. Today my time has been about 50/50 split between OSX and Win7 (servers are rock solid so no linux today).
If I needed a particular app that only ran on windows, I'd use windows. If I can run it on any OS, I'd choose OSX as I am simply more productive with it the way I work (creating scientific papers and presentations using media from multiple sources and windows, that kinds of graphic, plots, etc.).
(note: I still refuse to run that ass-nugget of a program Outlook on any Win7 machine. Thunderbird is uglier but Outlook has the worst database ever - searches are insanely slow as I keep about 10 years worth of email and corruption is a regular issue)