I bought my aunt a new computer running XP. Her old computer running 2000 has several years of tax programs on it. How do I move these programs to the new computer so she does not loose all her data and can still work the programs?

Try using the built in XP program, Start\All Programs\Accessories\System Tools\ Files and Settings Transfer Wizard.

For Turbo Tax, "data" can be moved by simply copying all files with a "TAX" extension to the new computer.  Use a floppy, CD, ZIP, pen dirve, whatever to move them. They can be placed in any directory, but traditionally the directories are called "taxnn", where nn = tax year.  Turbo tax will usually find them itself, but if not, the user can browse to find them to import information into the next year's taxes.  It is possible that other tax programs have similar capabilities, although the specific files they save might end in something other than "tax".