The tweak freak in me means I am always looking for ways to optimise my PC experience - I must have played with 20 or more new utils durign 2005 such as TaskSwitch XP, Windows FX and more. My essential utility is the TweakUI pack from our own Windows download site which lets you do stuff like turn on the Windows wallpaper during logon, change menu speeds and much more. Trivial stuff I know but when you spend forever looking at the screen I like it to look how I like it to look. I also like the ClearType tuner and for my Nikon D70, the RAM Image and Thumnailer and Viewer is a must (beware, 47mb download!).
A great source for this kind of stuff is Comuter Zen - aka, Scott Hanselman's page which is chock full of cool stuff to make your PC life even easier. One thing he does mention is Magnifixer for zoom in functionality but this has just been usurped by Intellipoint 5.3 which when used with a new mouse like my Wireless Notebook Laser Mouse 6000 (very Star Wars!) allows you to click the additional button on the mouse and zoom in with full functionality so that stuff like hyperlinks works. Tres cool.
Oh, and before I finish - I just found another cool tool. A non-supported util from our PSS guys that allows you to mount an ISO image as a drive called the "Virtual CD-ROM Control Panel for Windows XP". Nice!