Have you enabled autoplay? Have you tried all your USB ports? Have enabled USB 2.0 in your systems' BIOS? Have you tried the drive in another computer?
autoplay: To change how your computer handles multimedia content
Open My Computer.
Under Devices with Removable Storage, right-click the device you want, such as a digital camera or CD-ROM drive, and then click Properties.
On the AutoPlay tab, click the multimedia content type you want to change.
Under Actions, click the action you want Windows to perform when it detects the media type you selected.
To open My Computer, click Start, and then click My Computer.
Your removable storage device must be attached to your computer for it to appear in the My Computer folder.