Overclocking? Same, 955BE.
Future proofing? I happen to think that "future proofing" is a null concept. But in this case, it depends on the motherboard selected.
Overall? Small edge to 955BE.
It should be a fight between the i3 2100 and the 955 BE. They both tie up in games (although I would admit that the 955 being a quad core chip has a slight lead). Now overclocking is something which cannot be done on the i3 2100 but considering a faster core performance and turbo, it is on par even with an overclocked 955. As for future proofing, honestly am not sure of that concept. You can get a 990FX board with the 955 and that will allow you to upgrade to Bulldozer CPU's. With the i3 2100, any board you purchase (preferably a P67 or Z68 chipset) let's you upgrade to awesome CPU's like i5 2500k which to my belief are more than enough to keep you gaming for atleast another 3 years down the line (with the right kind of video card ofcourse).
Disclaimer: Answers based on reviews and tests and views on the direction where the SW&HW industry is going...
Gaming: According to test results which can be found for example from tom's hw articles i3 is the better CPU for gaming.
i3 2100 and i3 540 are close to the same, as you can OC the 540 to the same clocks as the i3 2100 or basically about as much as you can the 955BE. And at the moment they perform better at gaming than the 955BE. So in this case I would have to say i3 540 overclocked. i3 2100 in stock.
This is a tough one: i3 540 and 955BE are probably very close. But 955BE is in a sense better because it has an adjustable multiplier, while i3 540 OC is done with FSB. i3 2100 is not an option really since it can't be OC'd any meaningful amount.
Future proofing: More of a platform/socket thing really.
This pretty much rules out the i3 540 completely, due to the dead 1156 socket.
i3 2100 has a future when paired with the proper P67 or Z68 motherboard. Allows for replacement CPU's to the 1155 socket.
955BE works in both AM3 and AM3+ MB's so with the proper AM3+ motherboard this is also future proofed.
But thinking strictly of the CPU 955BE is the best because it has 4 cores , and games and other SW is constantly evolving to utilize more cores.
So the answer to this is: CPU wise 955 BE, platform wise it's pretty much a tie between the 955BE and i3 2100 possibly leaning a bit towards i3 2100
If you're going to overclock the 955 to increase it's performance you're better off using the $30 you're going to spend on a cooler to get the i3-2120.
Even for multi-threaded applications (encoding DVDs, etc.) the i3 is no slouch since it has hyper-threading. It can't be overclocked but the LGA1155 has plenty of upgrades already (i5-2500/i7-2600). Ivy Bridge will also be LGA1155.
The i3 will also use half the power of the 955 at max load.
I disagree. I know of no tangible evidence that suggests this. Besides, what do you define as stability?
Did you ever have a Socket A motherboard ? For one the handling of low speed memory and high FSB. PC1600 and PC2100 VS FSB 333/400 were handled poorly and caused system instability/crashing regularly.
I was having an easier time selling AMD at the time p4 prices were nuts.
Sorry that is all I have as I've stayed completely away from AMD since that time. Actually I downgraded and was playing console games instead.
I did, actually. My first AMD machine was a K6-166, then a -333, and then a Socket A Duron 750 which ran for 5+ years with very little trouble (the bit I did have, I blame on Windows ME.. :-) )
My current machine is a Socket AM2 Athlon X2, which is still going strong after 4 years.
I know some people have had bad experiences with AMD, but I never have, thus I'm less inclined to Intel favouritism than most.