Rick ...
Are you planning on updating Win98?
(Quick answer: 'Hide' the WinME drive, boot to the XP install CD,
updating the existing OS when asked.)
Are these two separate physical drives?
(Quick answer: 'Hide' the WinME drive, select 'swap' in Boot Edit
(assuming that Win98SE is on HD-1) and boot to the XP install CD, deleting
the existing OS when asked.)
The above are GROSSLY insufficient, as there are (among other things) boot
settings needed to enable you to boot to the CD, but the BEST answer one
could give you is to download the BootItNG manual at:
http://terabyteunlimited.com/downloads//bootitng.pdf