You could make a windows partition (fat32,ntfs) from your linux partition, if you installed red hat to one...
You could say, make your windows partition maybe 1gb-1.5gb, the rest could be for Red Hat, then you could install XP, i'm not sure if installing XP would go over the MBR (master boot record) i'm sure it would though, but gettin lilo or grub back up (depending on what you used) should'nt be a problem, as long as you have your bootdisk it will be ok, if you have problems post them up here, i know this was very short but i'm actually quite sleepy...
Oh and also, if you don't wish to install XP JUST because your wife needs word, there are alternates, some very good ones are Open Office www.openoffice.org
or abiword (seacrh for it at www.google.com/linux
Both these support the file extensions of .doc (same as windows)
This would be easier if you don't wish to install XP partition etc. etc.