Hi Laing2,
Question. If you are already streaming from your PC with TVersity (which I do as well) then why do you need an external hard drive. I guess 'not having to turn on your PC' is the most likely answer. Mine is never turned off so it's not a concern for me.
External hard drives work pretty seamlessly with a PS3. However, one thing to note is that unless it has changed recently, a PS3 is limited to reading hard drives that are formatted in FAT32 format. This limits file sizes to proximately 4GB. This isn't a big problem for most music formats but if you intend to store movies on the hard drive, you will have to compress them to fit within the 4 Gigs.
Tversity overcomes this problem by allowing you to use a PC with NTSF formatted drives for bigger file sizes. Because the data streams to the PS3, it won't care that it's not coming from a FAT32 drive.
