I normally do my day-to-day work on a great HP NC8430 laptop. I have had it for a couple of years and it has been trouble free for me. It has a nice full size keyboard and big screen - it's fantastic for doing demo's, managing email, and doing spreadsheets/documents.
However, a large part of my job is also about travelling to customer and partner meetings where all I need is a PowerPoint deck, maybe some documents, Outlook and OneNote. I invested in an Asus Eee PC 1000H as a second lightweight laptop good for day trips to customers (it's also what I bring when I travel overseas). I removed Windows XP and installed Windows Vista Ultimate on the Eee PC, and Vista runs just find on this very minimal spec'ed Netbook computer. I also see that Windows 7 is being engineered to support small Netbook PC's as well - http://apcmag.com/Content.aspx?id=3155 .
With the amount of Synchronisation technology available to me with Outlook, Office OneNote, Office Groove and Live Mesh - I can have all of my important content available on both laptops at all times. I can just pick either of them up, and I'll have everything I need.
One thing I did need to setup was to share Internet Explorer favorites between my two laptops. I didn't know about it until just recently - but Windows Live has an Online Favorites service that gets exposed into Windows Messenger, or accessible in a browser. I can easily export my current IE favorites / bookmarks to Windows Live Favorites http://favorites.live.com/ and then am able to access them from Messenger (the tab with the little yellow star - see the screen shot) on my Eee PC. Easy.