Using DOS and Windows since the mid 80's it was time for a change. Vista was never reliable on any of the three machines I tried, Microsoft fanboys were killing creditability in the user group scene - heck it got to the point where saying 'Google' was not permitted. It would immediately be corrected to 'Bing', sometimes by a chorus of fanboys! This anti-Google sentiment has to stop. Fanboys may go "Rah-Rah, Bing-Bing-Bing", but how many of them command respect from peers? Many competent people stopped attending Microsoft events.
So how did OS X work out? Well it's certainly a good operating system, does most things I need but obviously is not going to run Visual Studio anytime soon. Lack of open source software was a major gripe; 7Zip, KDiif3 and many other great open source projects just don't exist for the Mac.
Snow Leopard was a total flop, costing me hours in lost time as it broke our HTPC which was running Hulu and XBMC. Initially Mac fanboys jumped all over me for criticizing it the day after it was released, but over time the general consensus is that Apple needs public beta testing before releasing an OS upgrade. A few service releases later Snow Leopard works fine but lacks the snappiness of Win7.
Apple hardware is fantastic. Developing on a MacMini is heaven thanks to virtual silence. The tiny form factor helps declutter workstations, keep a clearer desk etc. Using a MacMini as a HTPC is a little expensive but totally worth it, low power means low heat and they'll happily live in a cupboard. New Minis also support two digital monitors, IR remote, Bluetooth, latest WiFi, GigaBit internet and have a stack of USB ports. The 13" MacBook Pro cost $1200, plus the cost of aftermarket 4GB RAM and an Intel SSD. With the SSD and Win7 it's plenty fast even for a demanding developer. The quality keyboard and touches like back-lit keys, multi-touch track-pad etc make it easily worth the extra cash. Oh and using OS X battery life is nine hours for the latest model - I see over five hours with WiFi and Bluetooth on a 2009 model.
So why the move to Win7? "It just works" scream most Mac users when you ask them "Why a Mac". True for basic users, but not people like us. Hours can be wasted with simple tasks like trying to format a non Apple external hard-disk. This where the experience breaks down. Problem with Windows are generally solved with a quick Google search. Certainly not the case for OS X, with the hard disk users were berated online for not buying a Apple branded hard disk. I have Bluetooth problems with a Microsoft mouse and have never been able to resolve it other than rebooting. Do you use two monitors? Fine, that works... oh you have one in portrait mode (like I do)? Is not going to happen in OS X yet, sorry. HTPC? What you did not buy an Apple TV unit? The Mac Mini work well as a HTPC but does not support font scaling like Win7. I found a hack which works in some cases not other. Of course almost those cool HTPC open source tools don't exist for the Mac, ironically XBMC is one that does and it's almost as stable as for Windows.
Hopefully this posts helps you consider if OS X is for you. It's a good OS, but Win7 is so much better in so many ways. If you want something that "just works" for simple tasks I highly recommend an iPad. That device is so simple I bought another for my Parents. They grasped it quickly and are having few problems. Also the design of the iPad apps means it'll be very hard for bad guys to devise a virus for them. Macs don't get PC viruses they get Mac viruses; I would wager the iPad will be virtually virus free.