I've just replaced one of my 2GB modules with a new 4GB module from Crucial in my early 2008 17" MBP and it's running absolutely fine.
Hardware Overview:
Model Name: MacBook Pro
Model Identifier: MacBookPro4,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.5 GHz
Number of Processors: 1
Total Number of Cores: 2
L2 Cache: 6 MB
Memory: 6 GB
Bus Speed: 800 MHz
Boot ROM Version: MBP41.00C1.B00
SMC Version (system): 1.28f3
OS X 10.8.3 (12D76)
I wouldn't personally recommend using memory with a different bus speed than your Mac supports - can you not buy from Crucial where you are?
I am very tempted to try 8GB - I did see a screenshot of a MBP 4,1 running 8GB but have no idea if it ran into a kernel panic at any time, does anyone know if 8GB is a real possibility?