2. Because it costs more to manufacter that many RAM chips on a DIMM, I would imagine atleast
3. Depends on what the speed of the 2nd drive is..... Ultra ATA only means the transfer speed of data, whereas 7200rpm's is the spindle speed of teh drive. If the 60gb drive is ATA and teh 80gb drive is 72000rpm's then you only have to decide which capacity suits you, but I would imagine that the 80gb drive is probably 5400rpm's, so make sure you check and then decide on your needs
4. Well what are your graphics needs? Are you wanting to play DOOM3, etc.? If so then you'll need either a Mobility 9700 or FX5200 or better I think.