The Intel core i3 is an all around better processor. The i3 will do well in most games, and the option to over clock is always there. Not saying that the AMD will not over clock, but it will not be as good. I personally think that Intel processors run cooler and last longer.
While in your link the 645 beats the 540 in over half of the benches.
Right now Arrandale/Lynnfield is dead, over priced and incompatible, its like getting a Q9550 for $300. Either look for SB or get the Athlon II, at least with ASUS boards there is a glimmer of hope in AM3+ compatibility.