which processor amd OR core2duo

Well core 2duo is nice but you really would never need that much power go with a centrino or a Xeon or if you wait you can get a Atom. this is a new processor that can provide 1.8 Ghz in a one centimeter by one centimeter chip

I can not judge your decision as you only give me too little clue about your PC. I believe that Intel and AMD are two excellent processor manufactures. It does not matter much which processor that you buy as long as you buy a new arrival processor (not junks). I do believe that overall performance of a computer is not solely based on processor, because motherboard type, ram capacity, ram types, hardisk speed, and vga cards are also contribute in overall computer performance rating.

I prefer AMD processor because they are fairly cheap and works like a charms. Also it suits just for my needs.

Quite difficult to distinguish this two processor. Back to early days my first notebook running on Intel 486 75hx. Now I own notebook Intel Centrino Duo still complaining processor speed.