Ok, so I have a MB 13" unibody which I love dearly. Now it's time to consider replacing either my netbook or my desktop PC at work. I have roughly $2k available, and my primary needs are web/email/office apps. So the question is, do I go 'up' to a 24" iMac (especially with the heads-up that they may be updated soon), or 'down' to a MB Air? (ok, no flames about the up/down...it's about the sizing, not quality or anything!) The 13" is a wonderful portable machine, but there are days when I just prefer to grab a USB stick with my files and head to work. So the iMac would allow that level of portability, while the MBA would require one computer to always commute with me. But the MBA has sex appeal, and doubles as replacing my crappy little netbook. Thoughts?