So I've been working with SQL Server 2008 on my Dell Latitude E6500 laptop now. At work, we are primarily using 2005, but my HP Compaq 8710w work laptop is somewhat limited in that it has just 3GB of memory.
The data warehouse takes forever to load on that machine, so I've been using my personal laptop, which has Vista 64-bit, SQL Server 2008 64-bit, and 8GB of RAM. That added RAM makes a huge difference!
Anyway, the most noticeably nifty feature of SQL Server 2008? IntelliSense! A major improvement, but takes some getting used to.