If I may make a few suggestions...

Via just released a couple REALLY nice Mini-ITX boards, the EPIA EX Series. There are only two out right now, both use C7 Processors and come in a 1Ghz package and a 1.5Ghz package. The EX series has some nice features that some older models lack such as a DVI port, and Component Video(red green blue) outputs for 1080i, 720p, and 480p Televisions as well as the more widely used standard AV(yellow, red, white) outputs to older TVs that are only capable of handling 480i signals. For people that would use this as a set top box type computer it also includes an optical audio output for high definition audio in surround sound systems. In addition to the great video and audio functionality it also boasts a DDR2 slot for DDR2-533 Ram and on-board Serial ATA for newer desktop and notebook drives. Via has also stated that they will be releasing a couple new boards with similar specs as the EPIA EX series in both the Nano-ITX(12x12cm) and in Pico-ITX(7x10cm) form factors.
Sooo anyways.... if you were planning on building this for use with a TV you might want to considering trying to get one of these boards.

Also... use up a little more space and stick in a standard laptop hard drive. You'll get much better performance and it'll last you a lot longer than trying to run any OS off of a flash drive. The newer SATA laptop hard drives should work flawlessly with this. There are adapters for the ATA style laptop hard drives to convert them into Standard desktop ATA Hard Drives. http://www.newegg.com/Product/Produc...82E16812203012

Lastly, if you are trying to save space keep a few things in mind when selecting a Wireless card.
1. You could select an ITX board with a mini-PCI slot and use a mini-PCI compatible wireless card such as the Intel 802.11G Mini-PCI Card. http://www.newegg.com/Product/Produc...82E16833106221
2. You could select an ITX board with a PCMCIA card slot and simply purchess a PCMCIA notebook wireless card.
ITX Board - http://www.newegg.com/Product/Produc...82E16813181012
Wireless Card - http://www.newegg.com/Product/Produc...82E16833124138
3.Just simply build your system and attack a small external USB Wireless adapter. In some cases this may actually be more effective because if you put your small system inside of an entertainment center and you attach a usb extension cable to your USB wifi adapter you may get a better signal than if it were inside the entertainment center too. http://www.newegg.com/Product/Produc...82E16833130111
4. If you already purchased the compact flash adapter, don't let it go to waste, use a compact flash wifi adapter. http://www.newegg.com/Product/Produc...82E16833147119

Pico-ITX -


Here is a video of the 3 types of boards. http://www.youtube.com/watch?v=dDrRjqOGM7E

I'm also working on a Mini-ITX project so good luck!

Here are some Commerical Mini-ITX machines.
1. http://www.tigerdirect.com/applicati...682&CatId=2313
2. (case only) http://www.newegg.com/Product/Produc...82E16811165041
3. http://minipc.aopen.com/Global/news/20070214.html