As I said in my first post, it really comes down to your OS choice.
[rant]
I've used Windows from 3.1 right through to Win7 Ultimate, and anything between Windows NT/2000 and Windows 7 was generally unacceptable. XP came close but not close enough. I've used various Linuxes (RedHat 5/6, Mandrake 8/9, Fedora 12, Ubuntu 5 through to the current which I hate... 11.04 is the best IMO, and just the other day installed OpenSUSE 12 KDE. erk), I've used OS/2, I've used the Commodore OSes, and Mac OSes from System 6 onward (hated those *and* the 9" screen I was using them on)... and OSX from 10.2... and thats where I have stopped (except I have Ubuntu 11.11 on a netbook and really I need to reinstall 11.04). I switched from Windows permanently in 2003, with a purchase of an eMac. Hideously expensive for what it was, but I found that I adapted to the new OS much faster than I expected, and when I had not even switched on the PC which I had been using until then, I sold it.
I think Windows 7 is a competent OS and certainly the quality has improved to a point where I would likely be happy to use it again if I cannot continue to afford my OSX machines... but because I like OSX so much, and I am not a gamer, there doesnt seem to be any reason to go back to Windows... and if I REALLY need to use windows not in a virtual machine, theres always bootcamp. I find the VM works just fine for my needs. I expect this laptop I am posting from at the moment to last me a very long time. I've added more RAM to the 2007 iMac: 2G beyond the stated specs for a total of 6G, and plan to add anotehr 4 to the laptop, for a total of 8G. An SSD for each of the machines is very appealing, but expensive.
I think Grant about summed it up. If you are already Macced, why change? The software will cost a fortune if you are going to replace/duplicate it, and there seems to be no logical reason except in the cost of acquisition... and a refurb or even second hand machine will do the job, no worries.
[/rant]