It's the format of the drive that is tripping you up. The PS3 is expecting either a FAT32 or possibly NTFS drive when you connect it via USB, and Windows (or probably even Linux) can't read the PS3's native format without special software.
So, I'd look around, and see if you can find a program specifically designed for reading PS3 drives. There used to be a few for the old Xbox drives with their FATX filesystem.
Recently I purchased a 200gb Seagate Momentus (Model ST9200420AS) to replace my 60gb HDD that I had in my ps3. I also got a external enclosure so I can transfer my videos and music from the 60gb to the new 200gb in my ps3. When I put the 60gb HDD in the enclosure, it didn't show up that I had connected any thing on the XMB and when I plugged the enclosure into my laptop it didn't show up either. I would like to still be able to use the 60gb HDD but the enclosure won't let me. The enclosure is a Rosewill (Model RX81US-HT-25A-BLK). When I connect it to either the ps3 or my laptop the blue power light comes on and the HDD spins up. After that it just spins but no activity. Is it a defective product or did I get something that was incompatible with the HDD? What enclosure's work for this type of job?