Problem with slow hard disk
Solution 1:
That drive isn't really compatible with Windows XP as it uses a larger 4K sector size - it should explain the performance problems.
There's a special alignment tool from WD for Advanced Format drives you need to use or set the correct jumper if it's only going to host one partition.
matrice of OS and how to get them to work http://www.wdc.com/en/products/advancedformat/images/WD-Align_chart_r2.jpg
It's really time to upgrade from Windows XP as this kind of workaround from drive makers probably won't be provided in the future.