I started my computing life on a Sinclair ZX81 with 1k of memory (total). If I wanted to get it to do anything of significance I had to laboriously hand code it, sometimes from a magazine that published user-submitted programs (with accompanying bug notices and typo corrections in the following month's issue). Today I work on a Mac Book Pro with dual 2 gigaherz processors and 104,857,600 times more memory (approximately). It does most things I want, including running two operating systems simultaneously.
I use Parallels on top of OS X, and let me start by saying the things I don't like about it:
1. My hands get confused about keyboard shortcuts (cmd vs ctrl for the most part). Yes I know I can remap them but it seems to work inconsistently, but you realize how much of computer usage is rote and unconscious when you're forced to switch. It's like driving on the other side of the road in another country, or if someone switched the brake and accelerator pedals. And on the computer it goes both ways - I'll use Mac shortcuts on the PC side, and vice versa, and then sometimes will second guess myself several times as I try to remember which one to use in a given setting.
2. I realized how ingrained I'd become in the Mac method of file navigation that I find Windows cumbersome by comparison.
3. I can copy/paste between OS's...sort of. Really only text works. Images and other more sophisticated things don't work. And formatting gets lost with text pastes.
That's about it. There are some other convenience things I'd like, but they've mostly been addressed in the new version of Parallels which I don't have yet (and maybe the above have too). But here's my point: I'm delighted I can do this at all.
It's like that old joke of a guy seeing a dog talking and complaining he had a limited vocabulary. Well the thing is that it's amazing the dog can talk at all. This is kind of what it's like using Parallels (or any virtualization software) - it boggles the mind that it works at all, let alone as well as it does.
To my delight, Powerpoint is sooo much better in Windows than on the Mac in terms of performance, even running in Parallels. Outlook is also far superior to Entourage, so I'm happy I get to use that too.
In the future, virtualization is going to become a lot more common so we will all have these schizophrenic experiences. But there are some challenges to overcome when you start combining systems like this, that aren't just technical:
1. Mental models are different between systems, in both gross and nuanced ways. While the computer can easily switch between one and the other, the human cannot. We do these mental modal switches all the time when we switch devices, but it's much harder to do when contained within a single device like a PC. It's like the brain needs the physical shift in order to assist the mental shift.
2. Muscle memory also cannot be switched over easily, and paying attention to helping the human along on this will pay off tremendously in their satisfaction of the experience.