If you have a >2 megapixel camera, it's likely that you never view your photos at full resolution, since even a 2mp image is larger than what most monitors can show. While full resolution may be out of reach, it's still possible that you can see more pixels than you do currently. If you have a CRT, it's very likely that you don't push it to the very highest resolution, as Windows just isn't usable (fonts are too small, as are toolbars, etc). And even some LCD users run in less than full resolution mode, for the same reason.
What you'd like to do is temporarily switch to a higher resolution mode while viewing your photos. You can do this by changing your desktop settings, but it's a pain to switch back and forth all the time. Luckily, there's an app that will do the work for you. Reso will change the screen resolution (and/or refresh rate) and then launch an application of your choosing. Once you quit that application it will return your screen to normal.
Use it to start Infranview and you have a high resolution image viewer. You can even place a shortcut on your desktop that does this, and then you can just drag any photo onto it to view the image in full resolution. You'll be amazed how much more your photo's "pop" when viewed at 1600x1200 or higher. This is one of the reasons to hang on to a good 19 or 21in CRT.
See also: this writeup.