Andi B - I also prefer working on a desktop over a laptop because of the keyboard, mouse, and much larger monitor. But sometimes it is impratical to haul my desktop around and a laptop is very handy. Hence wifi, and on the newer machines, USB 3, is important.
My opinion is the graphics part is pretty good right now for desktop users. It is easy and cheap to buy a graphics card that is supported by SNAP, and SNAP works great for dual monitors. I am writing this right now on dual 27" monitors each running at 1920 x 1080 via ArcaOS SNAP on a quad core machine. The video card (Radeon X600) cost $7 including shipping. While I don't believe SNAP will run the the very wide 4K screens, I think Panorama will.
Panorama on a quad core machine performs well enough to run video at 1920 x 1080, but I don't know how well it will perform at 4k resolutions.
If video is a concern then it is a concern (to me) for laptops because of the problem running WinOS2. My laptop will not run SNAP and WinOS2 does not run on that machine with Panorama - which means it doesn't run. However there may be a work around for that by running the Win16 apps in WinXP in VBOX. It will be a pain to install and setup, but I suspect it will work.