Yea, 168 is extremely old SDram
(Which I order a TON of. For some stupid reason, customers ignore my advice and keep nickel and diming their 15 year old machines to death. 40 dollars here for a new PSU, 50 dollars there for a new IDE HDD, 35 dollars here for a new ODD, 80 dollars there for a tiny ram upgrade. Then again, I wont complain until my distros stop carrying these parts. :P)
184 is DDR ram And both DDR2 and DDR3 is 240 pin ram, though they're not intercompatable.