It's difficult to thrive in the solid-state drive world. Unless you've got just the right controller and flash memory, most performance-minded PC users will rarely give you a second glance. Samsung muscled its way into that narrow view with the SSD 830 last year; it intends to lock our attention with the new SSD 840 and SSD 840 Pro. The Pro's 520MB/s and 450MB/s sequential read and write speeds are only modest bumps over the 830, but they don't tell th