Even if the screen is capable of supporting higher resolutions, you can always set the resolution lower by just right-clicking on an empty area of the desktop and choosing properties, then go to the settings tab (at least that is where it is in XP, not sure about Vista) and adjust the resolution to whatever is comfortable for you. You may not be able to get to exactly 1024x768 because the aspect ratio of widescreen LCD's is different from the CRT screens on which 1024x768 was more common, but you should be able to get close.

PS:  I just checked with a friend who is using a wide-screen laptop and the resolutions go all the way down to 800x600.  And 1024x768 is an option, but it produces two dark bands down both sides of the screen at the edges (so it is a 1024x768 window inside a bigger rectangle). 

Thanks for telling me about the Lenovo model. You are right about pointing out the pixels per inch criteria being my issue, and that starting off with a native reolution that is not too high will make the downgrading to 1024x768 display less blurry. My Dell Inspiron 8100 has a native resolution of 1400x1050, and changing it to 1024x768 has maintained a sufficient sharpness for me.

If you know of the make and model of the 17" model as other 15" models with 1280x768 displays, that will make my job easier. Are there any Dell models? Are there any websites that will let me choose laptops by narrowing down the criteria with the display resolution being one of the criteria?

You guys have been very helpful. Thanks again.

Take a look at the XPS 1530, which is a 15.4" screen with a 1280x800 resolution.  The 1720 should have a similar DPI on one of it's screens.

Also, supposedly Vista has some new resolution independence features which let you change DPI settings at the native resolution and still have things look okay.