I've been poking around the forums, dropping questions here and there and found some information basically stating that people did testing and didn't find DDR3 to be all that much faster than DDR2 RAM.
So, I'm about to spec out a new computer build that will need to last me a while. My current rig has held up for the better part of several years. I originally built it when the P4 2.4 was the hotness. However, despite having only 1GB of ram, I've been able to run Adobe CS4 apps, Gears of War and other intensive programs without too much trouble, albeit at low resolution in some cases.
So far I've settled on the following components:
AMD Athlon II X2 250 ~70 (have yet to buy, will OC at some point in the future)
Xigamatek HDT-S1283 (bought used for $20 on ebay)
Rosewill mid-tower Micro-ATX case (bought new for $27 on ebay)
Enermax 465VE (431W 20/4 P4/Athlon type, will upgrade to a Seasonics or Corsair 500w modular when I can afford)
Motherboard options (must be mATX, on board GPU, & OC-able):
GA-MA785GM-US2H AM3/2/2+ DDR2 board ~$80
GA-MA785GMT-UD2H AM3 DDR3 ~$89
So, there isn't a huge price difference between the boards, but in the case of the RAM, I'm looking for 4GB of reliable, good performing sticks from a top name like Crucial, G.Skill, Corsair...
On the DDR2 side, I'm not sure what type to get, but it seems most of the DDR 1200 stuff is averaging around $85. Of course lowered speed ram runs down to $65 or less.
On the DDR3, I was looking at DDR3 1333 sticks averaging about $85 a set.
So, I'm not sure which way to go. If there was some sort of DDR4 or some new memory technology coming out that was going to drastically reduce memory costs, then this would be a no brainer. However, I really want to get the most bang for my buck now and in the future.
I typically run Adobe CS4 apps (photoshop, dreamweaver), a flight simulator, Gears of War, a lot of web surfing, email, some video editing for the web.
BTW, I'm unemployed, so I'm not rolling in the dough either =\
No real difference in speed using ddr3 with am3 or socket 775, only with core i5 or i7. Shop for memory at several sites and go with any of the following brands (corsair, crucial, kingston, geil, pny, pqi, or samsung) in 800 or 1066 speed. I use pny pc6400 ddr2 on my biostar 6150 chipset board. I got a 2x2gb kit for $28 after $20 rebate at frys. Prices are higher now, but still do some comparisons at amazon, newegg, and frys.com before deciding on the board. The gigabyte boards are pretty good, and newegg has some great combo specials from around $125 with your cpu.
I'm biased, because this is what I bought late last month - although I paid more for it. Forget the Athlon, get the Phenom II 550 Black. If you want to overclock later, you can start by seeing if the other 2 cores unlock.
Look at NewEgg right now.
You can get:
# AMD Phenom II X2 550 Black Edition Callisto 3.1GHz Socket AM3 80W Dual-Core Processor Model HDZ550WFGIBOX - Retail
# 254101GIGABYTE GA-MA785GM-US2H AM3/AM2+/AM2 AMD 785G HDMI Micro ATX AMD Motherboard - Retail
as a combo for $162