Just to check, I have a Macbook (Pro technically) - I swipe two fingers down to scroll down, that isn't inverted is it?
I'm not leaving Snow Leopard until they fix the compatibility issues with Photoshop et al.
You only miss out on Apple software if you don't upgrade. Most software I use is FOSS these days. Thunderbird, Firefox, Clementine (Amarok port), VLC and everything else isn't included to begin with (FTP, text editors, etc). I can't stand iTunes, Mail and Safari so I don't bother.
It's generally worse when you upgrade, ironically, because their updates break compatibility with lots of good 3rd party software. As for timing though, I pay the same for Windows/Mac I think. I bought Windows 7 three odd years ago for £40. I bought my Macbook around the same time (with Leopard) and then paid £20 for Snow Leopard. I'll probably buy another update before I get a new laptop, and by that time Windows 8 will be out. As I mentioned, updating is a fast way to make your applications stop working so for most people it doesn't matter being behind the curve.