Another thing to mention here when buying an external drive is to plan on seeing the factory partition they come with reformatted from Fat32 generally seen for Mac as well as Windows compatibility to NTFS if you are strictly a Windows user. When going to unplug and replug a drive especially a laptop at work to home desktop you would need to run the software installer over and over again if you happen to run either without it plugged at the time.
Once reformatted the software can be replaced from the support site in a zip file you download and unpack onto the drive. But it then generally isn't necessary since Windows will generally detect and install it on the spot.
Manufacturers like WD, Seagate, and others will see this advised. Some models may already see a factory NTFS partition already not being available for Mac. The excerpt here is seen at the WD faq section under the installation for XP/Vista heading.
"Windows XP has the full driver support necessary to support Western Digital external hard drives. The single drive external hard drives ship with a FAT32 partition for the full drive capacity. In most cases, you may simply connect the external hard drive to an available FireWire or USB port on your computer. The dual drive external hard drives ship with either an NTFS (My Book Premium II) or HFS+ (My Book Pro II) partition. Upon connection to the computer, the external hard drive should be recognized and ready for use. Occasionally, the factory partition may not be recognized in Windows. If that is the case, use Disk Management within Windows 2000 to install (partition and format) the external hard drive."
http://wdc.custhelp.com/cgi-bin/wdc...F9zZWFyY2hfdGV4dD1WSVNUQQ**&p_li=&p_topview=1
The support site for each brand will usually see a general set of links for installation, how to partition and format in older versions of Windows like 9x-ME as well for 2000, XP, and Vista also using the Disk Management tool.