Windows cannot natively mount a Mac file system. You need something like HFS Explorer (freeware) or MacDrive (commercial). HFS Explorer gives you read access only while MacDrive allows both read and write access.
HFS Explorer :http://www.catacombae.org/hfsx.html
It won't help in your current situation, but just FYI Seagate provides a Paragon driver that enables a Mac to mount an NTFS file system:http://knowledge.seagate.com/articles/en_US/FAQ/216511en