(Info added July, 2019): This solution also works for 10TB WD EasyStore external USB disks.
(Info added in Oct, 2018): Problem solved by (who else?) @Comos, of course!!! 
The newer GPT formatted WD My Book and My Passport external USB disks can be reformatted by using the WD Quick Formatter, http://download.wdc.com/misc/WD_Quick_Formatter_Win_1_2_0_10.zip.
Then they become visible to XP (and report 4KiB sectors, too)!!!
Warning (added in 2017): This applies solely to USB 3.0 WD My Book Essential and WD My Book Disks manufactured before 2015 (which report as 4Kn)! Later Disks report as 512e, use GPT and, hence, are not usable by XP! 
Hi everyone,
as I started a discussion about an issue when running a 3TB HDD on WinXP 32bit in a USB 3.5" drive enclousure, link:
today ,I can confirm, that a external USB HDD from WD, currently 3TB My Book Essential does have full capacity support on Win XP 32bit. (maybe in Win Y2K also)
Today I have bought it and have 3TB in full armor 
Seems that the additional WD HW logic takes care of the rest and the related links were speaking the truth:
http://community.wdc.com/t5/External-Drives-for-PC/Exceeding-2Tb-limit-questions/td-p/234694
message to @dencorso:
The light has been kindled !