According to me, the appearance of a desktop does not depend on the themes you use as much it depends on the wallpaper and the fonts. By default, the fonts in Windows XP appear very rough and ugly. There is a really nice feature in Windows XP which can make your fonts look real good. You need to follow these steps:
1. First goto Control Panel –> Performance and Maintenance –> Adjust Visual Effects. From the list make sure “Smooth edges of screen fonts” is checked.
2. Next, right click on any blank area on the desktop and select “Properties”. Click on the tab “Appearance”. Click on the “Effects” button. Put a checkmark on the box which says “Use the following method to smooth the edges os screen fonts: ” and select ClearType from the drop down list. Click OK.
Now notice the difference.