Backup Utility VS Copying ?

[The Big Blue]

I got a 320G Free Agent Go the other day for $71 @ BBY.

Anyway, did the backup last night and had some questions.

After selecting the ext HDD as destination for backup the screen showed "Preparing... please wait" for about 12 minutes. Then went to the "Backing up" screen and sat there for about 12 minutes before it starting actually backing up. Is that normal?

The actual backup time seemed reasonable I think... 33G, 70 mins.

I'm not a gamer. I've decided to import my ~300 CDs to the PS3
and sell off the CDs. I'm really only concerned about protecting/not losing the music and also photos (not into vids at the moment).

Is the backup data on the ext HDD only useful as a PS3 backup? If I copied instead could the music be accessible via PCs or other devices?

Is the backup "smart", e.g. only backs up "new content"?

What are the advantages to backing up?

I'm wondering if it might make more sense in my case to just copy the content rather than use the backup utility.

Any help appeciated.