Planning to buy a PS3

[Usul]

I'm planning to buy a PS3 in a few weeks. I'm almost convinced becouse I guess it'll have the best lineup of game. Apart from games, the blu-ray player and free online are good reasons too. But I was wondering...

Should I get the 80gb HDD or the 160gb one? Is it enough with the 80gb version to download games and demos from the PSNETWORK? Won't be short space if I install lots of games?

The blu-ray player obviously reproduces blu-ray and dvd movies, but are suported other video media files (avi, mp4, ogm, msk,...) from your own recorded dvds?

Thanks!