Oops, we were talking external drives. Here is a 2TB external for $219:
Seagate FreeAgent Desk ST320005FDA2E1-RK 2TB 7200 RPM USB 2.0 External Hard Drive
http://www.newegg.com/Product/Produc...82E16822148417
Arash,
regarding 5900 rpm versus lower capacity drive at 7200 rpm, remember the data density is going up, so the higher capacity drives can both write and read faster at a slower rpm. Where you lose is seek and rotational delays, but for large images, this is less of a concern as large blocks of data are read/written at a time and this stuff is mitigated by the cache anyway.
Roger