Choose wisely regarding storage. You should plan on having whichever drive you get until the iMac dies. Apple is now using an unconventional proprietary hard drive, one with a built-in temperature reader for more accurate heat dispersion control. This means that only Apple -- or Apple-certified support techs -- have access to the parts necessary for hard drive swaps; even the bravest technophiles can no longer open up the iMac to replace the hard drive with a larger, off-the-shelf alternative.
Customers have always been discouraged from replacing iMac hard drives, since the procedure will void the warranty. But now it's technically not possible. Caveat emptor.
Final thoughts and recommendations
If I were to recommend any changes to the configuration out of the box, it wouldn't be RAM or processor upgrades -- although both are useful if you need the extra horsepower. What I would recommend is swapping out the Magic Mouse for the Magic TrackPad. Gestures are one of the big advances built into Lion, and the switch from mouse to trackpad is worth the swap. If you're ordering an iMac from the Apple store, you can pick either the Magic Mouse or the Magic Trackpad for no charge. Or you can get the Magic Trackpad in addition to the stock Mouse for $69.
Thinking of moving from a Windows machine to an iMac? Remember, you can run Windows on a Mac using one of several virtualization apps like Parallels or VMWare. (You have to supply your own copy of Windows.) Currently, my Mac can run Windows XP and Windows 7 -- at once, if I want. It's a great solution if you want a Mac and your job requires Windows-specific software.
To sum up, Apple has delivered a solid update to what was already a popular and successful line. The Sandy Bridge chips add a speed boost, Thunderbolt offers the promise of peripheral heaven in a few months, and the iMac design itself remains current. It's equally at home in the boardroom or the living room, and the range of sizes, prices and build-to-order options means it should be easy for most buyers to get exactly the machine they want.
Michael deAgonia, a frequent contributor to Computerworld, is an award-winning writer, computer consultant and technologist who has been working on computers since 1993. You can find him on Twitter (@mdeagonia).