How can I identify the chipset of an (old) MacBook? I am not a mac person, but I am trying to buy a used MacBook for XCode purposes and I want to figure out how much RAM it can take. However, I am having trouble identifying the chipset in the MacBook. 

The computer is listed as being a May, 2007 white MacBook with a 2.4Ghz Intel Core 2 Duo processor.

I found a FAQ online which states states that there are two Intel chipsets which this MacBook could have, the Calistoga chipset which supports up to 3.3Gb of RAM or the Crestline which supports up to 4Gb (maybe 6Gb). Then it states that, "To find out which C2D MacBook you have you can check the FSB clock or the GPU: If you have a 667 MHz FSB and a GMA 950 you have a Calistoga C2D MB. If you have a 800 MHz FSB and a GMA X3100 you have a Crestline C2D MacBook."

However, the specs listed for the computer do not match either of these descriptions. For the GPU, it states 
"Video
Graphic Processor:  Intel Graphics Media Accelerator (GMA) X3100
Installed Video Memory: 64 MB," which would imply that it uses the Crestline chipset and can support 4Gb RAM. However, for the mobo FSB it states "Motherboard Bus Speed:   667 MHz," which would imply that it is a Calistoga board which only supports 3.3Gb of RAM. 

I attempted to look up the exact computer to see the specs on everymac.com, but I was unable to find the correct model. Every listing for a white 2007 MacBook on that website said it had the GMA950 GPU, not the X3100. Additionally, the computer for sale says it has a 2.4Ghz Intel Core 2 Duo processor (there is a picture of the "About this Mac" window) and that isn't listed as an available option for any 2007 MacBook.  (Since the specs are automatically generated based on the date the seller enters, perhaps it is not actually a May 2007 MacBook? I don't know if macs are overclockable but it is definitely running at 2.4Ghz)

The RAM is definitely 667Mhz DDR2, as that is listed in the same picture from the actual computer screen as the processor speed. The hard drive was upgraded by the user and thus cannot be used for identification purposes. The computer is running Lion. Can anyone provide any assistance in identifying which chipset is in this MacBook?

To clarify: If the specs generated based on the May 2007 date are wrong, the only specs I know for certain are that it has a 2.4Ghz Intel Core 2 Duo processor and it currently has 2 GB 667Mhz DDR2 SDRAM, because these are shown in the screenshot. However, the seller says he upgraded the RAM himself, and that it initially came with only 1Gb of RAM.
The first MacBook to fully support 4GB of RAM (with unofficial support for up to 6GB) was the MacBook (13-inch Late 2007). This was also the first MacBook to feature a 800MHz FSB and the GMA X3100 graphics chip.

I'd be interested to know where you're getting your system specs from, but I'd suspect that somewhere along the line the FSB and RAM speed are getting confused.

Check your system's specification from the System Profiler application found in /Applications/Utilities. Under the Hardware section look at the "Model Identifier". 

If you get MacBook3,1 then you're in luck - that's the newer (Late 2007) model with greater RAM support and graphics. Anything prior to that (Macbook2,1 or MacBook1,1) and you're looking at (approx) 3GB limit or even 2GB (for the very first gen model).