Vista - External Harddrive "Working Properly" but not in browser

I'm running Windows Vista and I am trying to run a seagate external harddrive. The device manager says its working properly, the drivers are up to date, etc. but when I go into my computer it is not showing up. The harddrive is unformatted- I use it on both Macs and PCs.

If the hard drive is unformatted, then it wouldn't show up in my computer. You need to format the hard drive. Right click my computer and go to manage. In the Management console go to disk management and format your hard drive. If you say you use it on both macs and pcs, then it is formatted and you can try to assign it a drive letter. If it's formatted for Mac, you'll need to install MacDrive or something similar to access the files.