Making sure Motherboard is Correct

Hey, recently I've been having trouble with my motherboard. After help from here and having a friend check it out I've decided to upgrade, and I was hoping you guys could help me check out to see if this motherboard is compatible with my computer.

I have a 500W Antec PSU, a 300Gb harddrive, two dvd drives, and an ATI 4770 video card.

The motherboard I'm looking at is the Asus M4A78:
http://canadacomputers.com/index.p [...] cid=MB.350

Will this work with my current computer parts + the AMD Phenom II X2 550 Black Edition:
http://canadacomputers.com/index.p [...] id=CPU.907
and 4Gb (2x2Gb) Kingston HyperX RAM:
http://canadacomputers.com/index.p [...] AM.346.754

What concerns me in the motherboard specifications under "Storage" is the "1 xUltraDMA 133/100/66 for up to 2 PATA devices" part, I have two IDE dvd drives, but I can't find any numbers to see if they match up with the "133/100/66" part of the motherboard connection. Is there a way to find this out? Does it matter? That is the part that corresponds to dvd drive connections right? Further down there is a "Internal I/O Connectors" section. Does that correspond to the dvd drive connection? There is only 1x IDE connector so it would be a problem if it is.

Also I'm going from a motherboard with the 939 socket; the MSI AMETHYST-M. My computer case is the standard HP grey case, exactly like this: http://www.pacificgeek.com/product [...] -CASE.jpg. Does anyone know if there is a standard size for AMD motherboards, and if the new motherboard would fit?

I really appreciate any help you can give me, thanks a lot!

Yes, your chosen components and your current components will work just fine together.
Be aware, though, that you will not be able to run your RAM at its rated 1066Mhz in dual channel mode.
You will have to either run it in single channel mode or drop it down to 800Mhz.
http://usa.asus.com/products.aspx? [...] odelmenu=2

No worries about the EIDE devices, the will work with no issues.
Unless they are really old, they will connect at either 133 or 100, probably the latter.
If both your DVD drives are EIDE, they will both work just fine together on the single EIDE port.
There is no special connector as far as they go, either EIDE or SATA.

It is hard to say for sure if the motherboard will fit in your HP case but you will probably have no issues.
As it is a fairly recent system, it probably has a standard ATX motherboard in it (same as your new one).
Worst case, you can get a good quality mid tower for around $50.

Also would running 800Mhz in dual channel be faster than 1066Mhz in single channel? Googling it seems to indicate the difference in speed is minimal.

It's not on the list because this is DDR3 ram may not have been tested by gigabyte yet. It may work fine with the board or not at all.
So you'll need to change your memory choice....but that's not really a big deal..

The trouble with the "supported memory list" is that I can't find these specific pieces of RAM for sale. They don't seem to be sold except online.

Yes it is. Thanks for the advice everyone, I've built the new computer (had to buy new case to fit the mobo) and it works fine!