Some programs I've used/still use that have been useful in the past.
A nifty little program that lets you minimize any program you want to the system tray. I like it because it reduces my taskbar clutter. Although the site doesn't mention Vista support, I've been running it in both Vista x64 and XP 32-bit with no problems.
CPU-Z gives you easy access to information about your CPU and other main components (except graphics cards) that would otherwise take a bit more searching. GPU-Z does this for your GPU. Very useful for overclockers, still useful for non-overclockers.
A useful audio encoding/decoding/conversion/cd-ripping tool. It supports a bunch of different formats.
A nice GUI version of the command line tool FFMpeg, an easy to use, quite fast (at least on my pc) video conversion tool.