I have some questions about laptop RAM. I have 2 laptops, and one uses DDR2 DIMM A, and the other uses DDR2 DIMM B. From trying myself, i know that these two types are not interchangable, but while looking around on different sites searching for RAM, i do not see anything listed as DIMM A and DIMM B, only SO-DIMM, or MICRO-DIMM. Also, how do I know how many pins my RAM cards have? Don't want to buy the wrong ones.
If anybody could help me with this, it would be greatly appreciated, thanks.

DDR does not dictate DIMM assignment. DIMMs are the sockets the RAM modules go into, they are on the motherboard. The motherboard for any system has the capacity to vary in the number of DIMMs on it, some has two, some have four, etc.

In short, I've never seen a DIMM number on a module of RAM and, if I did, I would ignore it...with the possible exception of laptops . From what I've read, laptops can vary in placement of DIMMs and some have memory permanently installed or preinstalled.

To say any more that might make sense , I'd have to know the exact model & manufacturer of your laptop and I can then look up info on it.

I lied . Since you have a laptop, you will need SODIMM modules. These are the type of modules specifically made for laptops and they won't work in a desktop...and vice versa (desktop RAM won't work in lieu of the proper SODIMM.

http://www.escotal.com/memory.html

Louis