We interact with computers by looking at the screen, touching the keyboard and directing the pointer. Performance is an important factors in making a good computer, but the experience when performing these three actions is what can make a computer either great or terrible.
The first keyboard I purchased individually was a virtually indestructible keyboard when I was in college. I purchased this shortly after learning that gin, tonic, limes and keyboards don't mix very well. While the keyboard looked really cool, it was the first keyboard that I used that seemed to have contempt for the user. You had to jam the hell out of the keys which made typing exhausting, tedious and slow.
It was when I started law school that I moved to a laptop as my primary machine. My Dell Inspiron was a great laptop with a keyboard that I never complained about and a really nice trackpad for its time. It was when I got the MacBook Pro that I really started to get snobby about the keyboards. From the backlit keys to having a solid feel, it was the nicest keyboard that I'd used.
It seems that after 2003, Dell really started to cut corners on their keyboards and trackpads. I've used a number of firm issued Dell laptops and they just keep getting worse. My current Dell laptop keyboard is so bad that it's unreliable to type with. For some reason they continue to include the little eraser style pointer which was bad since it was introduced back in the mid 1990s. I'll occasionally touch the damn thing and suddenly the cursor is in a random position on the screen. The trackpad is embarrassing and has buttons on top and bottom. The top buttons also get in the way of typing. The keyboard is backlit, but it's done in a sloppy way so that light leaks everywhere. I hate that laptop with the power of a thousand suns, and I'd feel that way no matter what OS was installed or how much horsepower was inside.
This experience pales in comparison to the keyboard and trackpad that are on my Asus 4G Surf netbook. The keys are small and cramped to the point that typing is more of a three finger affair and the trackpad kind of works.
This brings me to my current keyboards. The MacBook Air, a wired full size Apple keyboard, the Apple Bluetooth keyboard and a Microsoft Ergonomic Keyboard.
The chicklet style keys on the current Apple keyboards are nice, although I still prefer the style that were found on my old 15" MacBook Pro. All of these are more flat than traditional keyboards but the bluetooth keyboard seems to have a slightly greater incline than the wired version. I prefer the greater incline, but the utility of a 10-key outweighs it for use in my home office.
The reason that I recommend getting the Apple keyboard and the Origami Workstation for the iPad instead of one of those integrated cases is that you're getting a real keyboard with zero compromises.
The Microsoft keyboard at my office is great, but there is room for improvement. While the keyboard isn't too mushy, it could have better physical feedback. While there are a lot of extra programable buttons, Microsoft has cluttered the keyboard with too many buttons which are tied to specific functions. While I'm sure that a lot of folks like that math symbols have dedicated buttons above the 10-key, I'd rather see an extra set of function keys like I have on my wired Apple keyboard.
The resurgence of popularity of mechanical keyboards is interesting, although I have yet to pull the trigger on one. There is the Tactile Pro which has been Mac centric for a while and the newly Mac centric Das Keyboard. While the Das seems to be getting all the attention, it's quite possibly one of the ugliest things I've ever seen. As Ben Brooks points out, it's really just a Windows keyboard with different key labels for OS X.