Windows Vista
Windows Vista is underwhelming to me. The two improvements that matter most to me are support for remote desktop at resolutions greater than 1600×1200 (Microsoft removed an arbitrary limit), and the ability to use Fast User Switching on systems managed with Active Directory (another seemingly arbitrary limitation removed).
Switching to Vista would require that I buy new hardware (for several computers), and the operating system itself is pretty pricey. The cost of moving to Vista far outweighs the benefit for me.
For a new computer, I could switch to Vista, but I can also buy a Mac. With a Mac I expect a better user experience, and the fact that MacOS X is Unix underneath appeals to me on a geeky level.
For my existing computers, I can continue running Windows XP for now, but I need to plan on Microsoft discontinuing support for XP at some point.
I’m reconsidering Linux as a primary desktop operating system.
Since I tend to read words on my computers, I care about how clear they are. I recently compared Windows ClearType font rendering with subpixel anti-aliasing on Linux. Below is an image with the two side-by-side (Windows on the left, Linux on the right) — click it to see what I had to say about it.
(Note that ClearType and subpixel font rendering may actually look worse than traditional anti-aliasing on a CRT monitor. They’re intended primarily for LCDs.)