If these are new drives, right out of the box, they are likely "raw", that
is without partions or formats. (Afterall, these drives could ahve been
used in a MAC, or other non-windows PC.) XP can sense such drives in its
disk management tool, but it can not in windows explorer.
The solution is simple: Partition and format the drives.
You have several choices: (1) The drives probably came with a CD and/or a
floppy with a name like MaxBlast. This is a set of Maxtor routines for
making partitions adn formating them. In general it is smart enough to only
work on a new disk, but be careful not to accidentally format your old disk.
(2) XP's own disk managemtn tool can do the same thing. The trick is to
first "prepare" or "initialize" the disk by right-clicking on the left side
of the line with the drive indicated on it. This is a nearly square box.
After that is done, you will be able to right-click on the right side of the
line in a distinctly rectagular box to make one or more partitions. (3) A
DOS boot floppy with the latest version of FDISK should be able to make the
drive recognizable to windows explorer. Personally I would go with (1) or
(2).