IMac – Comparison of the new macbook air and iMac Core Duo 2 2.66

A similar question was asked over at Programmers.SE, though it was about iOS development. Some might say that's not the same thing, but Photoshop is a robust application that allows you to install some very heavy-duty plug-ins and it has some of its own as well. The consensus could be gotten from the top two answers (mine, which has the higher vote count, and the other which was accepted):

Mine with 5 votes:

...leaving aside price, I would recommend a MacBook Pro for any serious development work instead. A MacBook Pro is more easily upgradeable to suit needs than an Air (if it is even upgradeable at all). The Air seems more targeted to lighter-weight uses.

Accepted with 4 votes:

It's obviously not going to be the fastest machine but it's perfectly suitable.

I'd say the 13" over the 11" because reasonable screen size is a big deal for development, and it can go up to 4Gb RAM rather than 2Gb (absolutely go for the 4Gb RAM model on day one and if you can afford it the faster processor as I suspect upgrading later isn't something Apple will be pushing).

Yes it's got limitations (basically the same as any laptop - essentially screen and power are limited next to a desktop) but I have the new one and it's entirely workable and I know others who use them (and used the old MacBook Air) day to day with no problems.

I, personally, still wouldn't recommend the MBA for any type of development work, web or otherwise. I've yet to do anything developing for iOS that causes me to bog down my machine the way Photoshop can and will.

Besides the obvious issue of you having too much information to load onto the SSD, I've done this basic procedure in the past. However, it's much easier now using Time Machine, but you have a few options:

Time Machine

If you don't currently have a backup that can hold all your data, do yourself a favor and pick up a drive that can. Time Machine should be built into the OS you're currently running.

Do the backup. For 400 GB, you probably want to set it up before you go to sleep and let it run overnight. Once it's complete, unmount the drive and unplug it from the computer. Go through with the drive install and then install Lion. When the computer reboots, before you start to work with the setup assistant, plug in the new drive. At some point it will prompt you for a location from which to migrate data. Select your backup. Let it run for a while and when you get back, it will contain all the data you backed up, in a usable form. This is my current favorite method for cloning user workstations.

Super Duper

If you can't get an external backup, you can use SuperDuper to create a full-system backup from the active system disk. You'll have the ability to trim the data to the size of the disk to which you're copying in the interface. This route is a little more technical and requires a bit more time hands-on.

File Copy

I wouldn't recommend copying a user folder for a logged-in user due to open preferences files. You'll get all kinds of "File In Use" errors and it will probably exit the copy prematurely. Instead (if you're dead-set on using this method - which I advise against) create a second admin user and copy the folder over into a temporary location before staging it into the actual /Users/ location. You'll also need to make sure the permissions for the entire folder are set so that the user whose home you are copying can actually access and write to their files. To do this, you can use the Finder's Get Info on the folder and then add the user to have full permissions. Once it's staged into the /Users/ folder, you can log back in to the main user and delete the secondary admin. You may have permissions issues in the future using this method.

All that said, it's totally worth it to get an external to back up to for Time Machine to clone your new SSD from.