Phenom II X2 550 BE or Phenom II X3 720 BE?

Just get the 550 it will serve you well for the applictions you state. There is the possibility of quad core unlock for both processors so check around do some searching here on toms and I bet you will find all the info you could ever want..... All this without ever hving to ask a question.

You would like that, wouldnt you? AND I did SAY possibilty!

I'd go for the X3. You can overclock 300Mhz (and they'll probably both top out within 10% of each other), but you can't make an extra core.

Why bother right now with the Phenom II X2 550 or the Phenom II X3 720.
Right over at newegg you can get the Phenom II X4 955 with a AM3 motherboard for about the same money because they are having a sale.
Go for the 790GX motherboard if you plan to use 1 graphics card or go for the 790FX motherboard if you plan to use 2 ATI graphics cards in crossfire.
For you on a budget you will probably want the 790GX.
So you won't have to wait a year to get a quad core CPU.
If you subtract the savings on the combo deals with those motherboards (since you will need one anyways) the Phenom II X4 955 will be about the same price as the Phenom X3 720.

http://www.newegg.com/Product/Prod [...] =10&page=1

Here is another good deal on a Phenom II X4 (the 940) although it's AM2+, however the memory is cheaper though.This system would be even much less in cost and would perform well.
The only problem about this is being stuck with an End Of Line AM2+ motherboard however that's not bad considering how powerful the Phenom II X4 940 is.Since it's way cheaper than choosing the Phenom II X4 955/AM3 motherboard route the money saved can also purchase the DDR2 memory so this with the mail in rebate would get you the CPU,Motherboard and 4 gigabytes of DDR2 memory for around $225.
http://www.newegg.com/Product/Comb [...] mbo.209473

Also
the AM3 cpu's will work in AM2+ MOBOS.

Phenom II's have a dual memory controller. either ddr2 or dd3 ram.

but - you cannot use an AM2+ CPU in a Socket AM3 - those soks are am3 only. but the cpu's are backward compatible.

720BE

You should get the Phenom II quad core with the deal thats out there right now. Most mmorpgs are more cpu intensive than standard games and WoW definitely does better on a quad core than dual core or tri-core.

It's too bad that the specific deal on the Phenom II 940 and the Motherboard is not offered anymore.They must have had a huge response so it sold out really quick.