The mini-itx motherboard makes a really nice thin client. While it cost more than a cheapie mini-tower, the Morex mini-itx case is really nice. I bought mine at Fryes in Fort Worth, but the following sources were among those listed on www.mini-itx.com
While the Epia 500 is adequate for thin client use, the difference in price for the 800 is negligble. Unless you need fanless operation, go with the faster cpu. You may later wish to use the client for Mosix clustering and the extra speed will be most helpful.
I ended up using the one I bought as a homemade office SnapServer running RH 8.0 and Samba. Nice thing about the EPIA is that your imagination is the only limit on how it can be used.
El Dorado, AR