These machines can be upgraded to a maximum of 3GB using a 2GB module plus a 1GB module.
Had to some research on this one.
The A1174 MA200LL 2.0 Ghzs takes a max of 2 GIGS of RAM
The A1207 MA589LL 2.16 Ghz will max at 3 GIGS of RAM
So everyone was right and wrong on this answer.
I WANT TO FLAG THIS ONE TO SEE WHAT YA'LL AND MANAGEMENT THINK:
SHOULD THESE MACHINES BE SEGREGATED, AS THEY ARE DIFFERENT AND MAY CAUSE CONFUSION.
Excellent update! It is very true, I neglected to mention the VRAM memory management with the older chipset does consume a certain amount of system memory. It is also true that the system interrupts also consume a certain amount. The standard use of the initial 640k of RAM is still used today for x86 class system boards.
Most video cards (at least AGP, PCI & PCIe) use a specified amount of system memory above the 640k floor consumed by the interrupts, with PC's this is managed in the system BIOS (although many newer systems omit these settings, unless you use the advanced settings), with the exception of newer APU boards. Additionally I Core systems that used the on-chip integrated video (Intel HD), which although similar in concept is structurally very different, and is controlled by software rather than firmware, utilizes (if memory serves) 64MB as the default memory allocation integrated into the chips cache. I have noticed that the newer Intel HD 4800 does auto allocate much more memory than the older HD 3000 did.
In any event, your clarification of the use of identical size memory sticks is a very important one and often misunderstood. When mismatching issues occur the systems memory allocation becomes very unpredictable and often unstable. So many times I have seen "professionals" upgrade system memory with mismatched latency or worse causing issues that were not there before the upgrade. So when in doubt match to the exact memory recommended by the manufacturer. Crucial even offers a free tool to perform a test and has worked for my team quite well.
I know this is a bit "Off-Topic" but, hopefully it will help someone in the future
I can confirm this latest answer, I have upgraded several Core 2 Duo's (to include Macbook Pro & iMac) to 4 GB RAM. 2x 2GB SODIMM's with absolutely no issue. These specific boards are similar to the G31 chipset boards produced by many manufacturers. Although many manufacturers configured the systems with 3 GB's of memory (as the upgrade from 2 GB), that was never this chipsets maximum memory.
The specifications for this chipset allows a maximum of 4 GB system memory. Although there are many possible chipset options offered (especially during the transitional period from PPC to Intel Core 2), the Macintosh boards offered mostly soldered CPU/GPU configurations in place of ZIFF (Socket T/775).
This really doesn't matter much with the exception of the limitations with CPU upgrades. The RAM is a limitation of the chipset itself, having nothing to do with the CPU socket itself.
The MAC customized boards stayed with the same chipset through the change to the next generation of Intel CPU's (the I Core) then changed several times from 1150 through 2011 chipsets (most supporting > 8 GB DDR3). Although the 2011 chipset does max out at at somewhere north of 92 GB, I believe that outside of the MacPro this is not an option.