Desktop or Laptop
When deciding on which computer to buy, the first decision you have to make is about whether to go for a desktop or a laptop. There was a time that many believed that the desktop would become a niche product. Most people want a laptop because they can take their computer everywhere they want to. Or at least lie on the couch while surfing.
If you want a laptop that also must replace your desktop, it must have a good screen, be fast and have lots of storage. And laptops are so good these days, they can be desktop replacements. Even if you buy a small laptop, they can still be fast and when necessary, you just hook up an external display, mouse and keyboard.
This is how I worked for many years and I still do. But I consider switching back to a desktop-based computer.
Mac and PC
I have two computers. The first one is an Intel-based Macbook (black) mid-2007, which is my main computer. The second one is a custom-build PC running Windows, solely for the purpose of gaming. This PC is based on Intel's Core i7 920, with 6 GB of RAM, so it's quite fast, even for today standards.
Both Macbook and PC are connected to a DVI KVM switch, that allows me to switch the keyboard, video and mouse between those systems. They thus both share my EIZO 24" (1920x1200) screen, keyboard and mouse.
Apart from these systems, I own an iPhone and an iPad.
Replacing my Macbook
For the last half year, I started to get annoyed with my Macbook. It just got slow. I put in a faster hard drive, but to no avail. The Macbook wasn't responsive enough. So I started thinking about replacing my Macbook. The first thing I realised that I do not need a laptop. I have an iPhone and an iPad, so sending emails, reading web pages, no problem. I do not tend to work on my Macbook outside of my house. So I don't think I need the mobility of a laptop. I want a fast but quiet, affordable computer attached to a high-resolution screen.
If you are a Mac user, there are three options: an Mac mini, an iMac or a Mac pro. I consider the Mac mini to low on specs and the Mac pro is just way too expensive. That leaves the option of an iMac.
Going for an iMac
Since I love high-resolution displays, the iMac 27" does appeal to me very much. The screen is just gorgeous. And you can put an Intel Core i7 into it, so it can be fast too. Even the video card is decent enough to play most games, either on Mac OS X or on Windows using Bootcamp.
Then after a discussion with a friend, I realised that the iMac would replace my PC. And my EIZO screen. New iMacs will probably arrive this summer, sporting even better processors, video cards, probably Thunderbolt. So I think I've made up my mind. I would still have my 'old' Macbook if I really needed any mobility. But I expect that once I have an iMac, both my PC and my Macbook are better off in the hands of somebody else. And I will need the money, an iMac is not cheap.
Thinking about this all led me to believe that in general, I would rather go for a setup with an iMac and a very thin plus lightweight laptop like the Macbook Air, than to buy a chunky desktop-replacing laptop like a Macbook pro. The big advantage of the latter is that you always have all your stuff with you. But you pay a price. The first thing is the weight. I really dislike the weight of my Macbook at 2+ kilos. The second thing is the fact that you always have to (dis)connect all these cables every time you switch between "desktop mode" and "laptop mode". The third thing is the noise. When putting some strain on the processor and/or video card, laptops tend to get noisy.
A desktop can give you true performance while still keeping things quiet and provide you with ample screen real estate. A netbook-like device such as the Macbook Air can give you true portability. I won't buy a Macbook Air, but this would be a really nice setup. The only thing you need to fix is the syncing problem. But there are services like Dropbox that may help you with that.
Keeping my Macbook alive
My PC has an Intel X25-M Postville 160 GB SSD installed as a fast boot disk. Since I couldn't stand the unresponsiveness of my Macbook anymore, I decided to put this SSD into my Macbook. This is cheaper than buying a new mac and I want to wait for that until the new iMac models arrive.
Installing the SSD made my Macbook come alive again. The Macbook only sports a SATA 150 interface, but it's not about throughput. It's about random IO performance. I am very happy with the result, there is less of an urgent 'need' to replace the Macbook in the near future. I can wait calmly on the new iMacs and decide then what I want.
Other people's thoughts