While I'm running Windows 7 on my netbook, I still use Windows XP on my desktop computer. I'd now like to share links to a couple of my favorite utility programs for Windows XP.
Firstly, Taskbar Shuffle. Picture this: you have been using your computer for a few hours and you've got a dozen of programs open: your browser, email client, instant messenger, a few Windows Explorer windows, and so on. Now, your browser crashes and you need to restart it. Suppose it was the first program you started after you booted your computer. Now, the browser's icon is moved in the taskbar from the leftmost side to all the way right, after all your other programs. I know it distracts me when suddenly a program icon is not located where I expect it to be. This is the situation where Taskbar Shuffle comes to rescue. It is a very simple program that allows you to reorder the icons of the running programs in the taskbar.
Another neat piece of utility software is Shell Enhancer. It also does what the name suggests: adds features to the Windows user interface. It has got a lot more features than Taskbar Shuffle but it also stays nice and quiet until you need it. My favorite of the long list of features is the ability to pin any window on top. Simple but effective. Another one is the ability to make any window transparent by any amount.