Although I never made a conscious decision to switch to the Mac, I've noticed that more of my home computing time is spent in Mac OS X. I've actually given up on using Linux as my main desktop OS, primarily because my Shuttle PC is so loud in comparison with the practically silent Mac Mini (and the Mac provides a decent UNIX environment in a few clicks if necessary).
But when I'm doing home lab stuff, I need access to a Windows PC. I tried to run Windows 7 (thanks to Technet) in a virtual machine on the Mac, but the memory overhead was too great as I've only got 2GB of RAM.
The solution I've decided on is to run Windows 7 under VirtualBox on my OpenSolaris server. As the server is always on, it means I've got quick and ready access to Windows 7 whenever I need it. The server has 8GB RAM, so running a 2GB VM is perfectly usable.
For connectivity to the Windows 7 VM, I'm using the Microsoft RDP client for Mac OS X. This has a couple of nice features: A full screen mode activated by Command-2 (Command being the Windows key on my keyboard) and the ability to switch the windowed view between full size pixels and a scaled fit-to-window option with Command-1.
The Windows 7 VM is used for running the vSphere client, PowerCLI etc., but also has the typical essential apps (Firefox, Evernote, Office 2010) installed as well. Performance isn't as great as a physical Windows 7 server (no Aero Glass for example) and I'm not using it for multimedia apps, but it doesn't require additional space or electricity and it doesn't generate extra heat in the office.