USB Hard Drive Not Recognized

I bought an SATA 2.5 hard drive housed in an external case powered by USB, on ebay:

40GB USB 2.0 External Portable 2.5" w/ OEM Hard Drive - eBay (item 200389641931 end time Dec-29-09 13:26:13 PST)

Win 7 can't find a driver and it didn't come packaged with one. How can I get Win 7 to recognized the drive?

Thanks much,
Harold

Hi. It's listed in Other Devices as an Unknown Device with the yellow exclamation point.

I'm going to work now, I'm going to try it out on my computer there, running XP. I'll post again tonight.

Thanks.

Working now. I took it out of the case, detached and reattached it. They just must not have seated it well. Thanks.

This is a very cool little device, btw. It's not much bigger than a pack of cigarettes and half as thick, so it's very portable. I actually have the 60 GB model, not the 40. Just plug into the usb port and you're good, don't have to mess w/a power cord. I was thinking of buying a 32 GB flash drive, but a good one costs upward of $60. This has twice the storage and is just as convenient, great for transferring files between my computers at work and home.