I'm a software developer that would primarily be running Windows 7 as the primary operating system. On a typical day, I might, at any given moment, be running Visual Studio, Expression Web, SQL Server developer (and Management Console), IIS, Photoshop, a dozen browser tabs in 2-3 different browsers, Skype video chat, streaming music, and a couple of VMs (WinXP and Ubuntu) for testing/experimentation.
Obviously, RAM is a concern, which is why I plan to use 8 GB so I can devote enough to the VMs to be usable. I'm also tempted to use an ExpressCard SSD for storing the VM disks to ease disk contention. And I know that that is asking a lot from a laptop, and I should just use a desktop, but I need to be able to take my work with me between several locations.
It seems that at a reasonable price point, it comes down to the i5 540M versus the i7 720QM. I'm leaning toward the i7 since it would allow me to dedicate a whole hyperthreaded core to each VM, and still have two cores left for the primary OS.
I've heard that the i5 has better battery life, but I'm curious for my scenario if there would be a meaningful difference. I don't usually work without a plug, but I do occasionally ride the train or fly and it would be nice to have at least 3 hours of juice for unusual circumstances.
And, finally, for this usage scenario, would a dedicated video option be preferred over the i5's integrated video? It sounds like Visual Studio 2010 (and Windows 7) can take advantage of the video card.