Why do you need to convert them? *.TTF files work fine in XP. XP has
updated some fonts ("O" icon instead of "TT"). If given a choice, hang on
to the newer versions. For older font favorites (ones with the older TT
icon), install to use them.
TIP: How to use fonts that are not installed: Double click the font file so
that it is displayed in the operating system's font viewer window. As long
as that window is open, the font will be available for use in most programs
(image programs, word processors, etc).