[metamemetics]

You should give him reasons why.

Personally I find Win7 has a far superior interface to OSX and out-of-box linux distros if you like using your keyboard and a minimal\no-shortcut desktop. The taskbar looks great left-aligned which, ideal for widescreen monitors. To open any program all you have to do is press the Windows key on your keyboard and type 2 or 3 letters for an autocomplete to find it, then press enter. No menus or shortcuts necessary. The only downside is installing CygWin for BASH, but I'd rather do that than install WINE for Adobe.

[kranner]

OS X has the Spotlight which people use in the same way: one hot-key, two letters to find your app by name, and enter.