ERROR: atapi.sys is open or in use by another application
do a search on your computer for atapi
or may look for it your self in this location
C:\WINDOWS\system32\drivers
once found, make a folder on your desk top and drag the file into this one new folder
now you can update your xp with sp1 / sp2
once upgraded your may delete this file...
dont worry! the sp1/spt installation will replace this file.
ENJOY!!!