Help me choose between these two boards:

ASUS AT5IONT-I, Intel®Atom D525 and

ASUS AT3IONT-I, Intel®Atom330

What is the big difference between those two?
I see that the at5 has no netagg but I am going to buy a case with 150W net agg and the at5 also has 2 highspeed USB ports but the at5 doesnät have bluetooth and I want to use the following keyboard that uses bluetooth:

Logitech diNovo Mini

diff:
http://www.prisjakt.nu/produkt.php?j=628081,540719
please help.

There are many differences.
The old Ion was an Intel CPU with an Nvidia chipset and GPU. Pretty straightforward.
But the new Ion has a bizarre architecture. Its (slightly faster) CPU has an integrated GPU and a crippled Intel chipset which Nvidia has been forced to use by Intel's monopolistic practices. The second GPU is still an Nvidia (it looks like an upgrade) but the way in which it's connected to the chipset is not ideal and may be limiting (I don't know). There's not much PCI bandwidth on the new Ion and Asus has attached lots of devices to it. That was achieved with a PCI packet switch. This isn't elegant but I don't know what effect it will have in practice. This board is also known for being incompatible with lots of RAM. There are enough potential problems that I wouldn't go with it without having done some reasearch.

Your case's 150W PSU might not be very efficient with a low load. And make sure that's it's got enough airflow for fanless operation!

Those boards have different stock clock speeds. The 330 runs at 1.6 GHz, while the D525 runs at 1.8 GHz, however, the 330 is popular for being easy to overclock. I have an at3iont-i which I overclocked to 2.0 GHz without any problems. I use a 120mm fan running at 550 rpm though.

I would agree with everything that HFat says too.

Maybe its better to go with the At3Ion board then, it has bluetooth (which I want for the keyboard) and has also an external net agg. which the AT5 donät have. Then I can get rid of the net agg in the chassi which often is very loud. Maybe I can put an fan in the place where the net agg is placed then.
I think I will buy the ace polly chassi and the AT3ION board then. Is there some thread or a page where I can see which memorys that are supported for the AT3 board?

Here's the product page for that board on the Asus website:
http://www.asus.com/product.aspx?P_ID=iHWm73RqE6MCmCtw

Click on the the tab that says 'download'. Pick 'other' from the dropdown box, and you can download the manual, or the qualified vendor list for RAM.

A friend of mine has convinced me to take another board instead, the cpu was way to weak in order to do something else then play movies.
And I cannot change anything If I take the AT3ion board so I will spend a little bit more and take the Gigabyte GA-H57M-USB3 board together with a i3 core processor. Thx for the help!

While I agree the AT5IONT-I may not be the best board for a gaming PC, it is an excellent choice for a HTPC. The Next Generation Ion (Ion2) GPU supports VDPAU Advanced (2x) de-interlacing in HD, where as the original Ion GPU would only do it in SD. Combine it with a good mini ITX case and hard drive and you will have a compact, quiet unit for your living room. It even has a slot for a PCIe tuner card if you so wish.

Thx Roger! I have ordered a HTPC already but my brother is thinking in the same way as I did in the beginning, I will put together a samll HTPC for him!

Thx again!