Re: Which PS3 should I get?
It all depends on what you want to use the PS3 for.
If you want more complete PS2 and PSOne compatibility, then you will want to search Amazon or Ebay for a used 60gb model. The 60 gb had both hardware and software emulation for PS2. It also has 4 USB ports in front and a card reader, which I find really handy for viewing photos off my camera, as well as SACD playback over HDMI. This is the model I have.
The current 80gb, which is almost impossible to find, has the same "shell" as the 60 gb, but is less PS2 compatible due to software only emulation. Sony may have also removed SACD playback, but I am not sure.
The current 40gb is not PS2 compatible, does not have SACD playback, and only has 2 USB ports in front and no card reader (you may be able to use an external card reader on the USB port). This is the model I recommend for most people who don't need a card reader and are not interested in PS2 compatibility. If you are concerned about the small hard drive on this model, you can easliy replace it with almost any 2.5-inch SATA drive, and I've seen 250 gb drives for around $100.