No, it will not - period. Your MOBO uses DDR2 RAM and is limited to 2GB/stick density.
In addition, you need to list your CPU for the 'ideal' RAM frequency.
If you want 8GB then you must select (2) 2x2GB matched kits or preferably 4x2GB DDR2 matched Kit. Further, for >4GB a 64-bit OS is required; 32-bit OS will be limited to 4GB with 3.0GB~3.5GB to the OS.
edit: noted "Intel Core 2 Duo E8400"
For a 1:1 I recommend DDR2-667 4x2GB, but if you plan to OC then DDR2-1066 4x2GB.
Compatible RAM - http://www.crucial.com/store/listparts.aspx?model=P5N-T%20Deluxe&Cat=RAM
ASUS P5N-T Deluxe - http://www.asus.com/Motherboards/Intel_Socket_775/P5NT_Deluxe/#specifications4 x DIMM, Max. 8 GB, DDR2 1200/1066/800/667 Non-ECC,Un-buffered Memory
Dual Channel memory architecture
*When installing total memory of 4GB capacity or more, Windows 32-bit operation system may only recognize less than 3GB. Hence, a total installed memory of less than 3GB is recommended.