Quality of LCD panes vary a lot. Some DO actually give a good image, with other than the "default" screen resolution, - and different resolution should therefor be tried first, because its also faster to do/test. All the alternatives of adjusting the desktop are more or less the same in both XP and Win7.

Then its often so, that we use icons at the desktop more by "recognition", than actually reading the text under it. This gives the alternative of choosing small/large icons instead, and by that, maintaining "normal fonts" in programs. The annoying fact that several Windows icons look very much same as another, is another proof that designers dont really care much about people with sight problems. Though one can of course change startup icons.

As for reading web pages after a DPI/PPI change, there are still a proper "zoom option" in most web browsers today (like Internet Explorer, easiest at its status bar, or "view" menu).