iMac 7,1 and 4Gb Memory Modules

I have a Mid 2007, iMac 7,1. I want to upgrade to Mountain Lion so that I can run the XCode development platform, it will not run on the Snow Leopard that I have, but I think I need more than thr 4Gb of RAM that I already have.

I have read that you can upgrade this to 6Gb, beyond the 4Gb limit Apple state, by installing one 4Gb and one 2Gb memory module. Does anybody know if there is anything that prevents the insatllation of two 4Gb memory modules and hence upgrading to 8Gb?

I am looking at installing either one or two of the following

• Module Size: 4GB
• Package: 200-pin SODIMM
• Feature: DDR2 PC2-5300
• Specs: DDR2 PC2-5300 • CL=5 • Unbuffered • NON-ECC • DDR2-667 • 1.8V • 512Meg x 64 •

To take on exisitng 4Gb machine to either 6Gb or 8Gb, cirrently I have

Memory Slots:

ECC: Disabled

BANK 0/DIMM0:

Size: 2 GB

Type: DDR2 SDRAM

Speed: 667 MHz

Status: OK

Manufacturer: 0x2C00000000000000

Part Number: 0x31364854463235363634485A2D3636374831

Serial Number: 0xE184435F

BANK 1/DIMM1:

Size: 2 GB

Type: DDR2 SDRAM

Speed: 667 MHz

Status: OK

Manufacturer: 0x2C00000000000000

Part Number: 0x31364854463235363634485A2D3636374831

Serial Number: 0xE1844369

Does anybody know if these are compatible (if I got for the 6Gb upgrade)?

Thanks

Matk