Can anyone recommend an Embedded computer board or chip?

I am looking to build an embedded Linux-based computer, and I was wondering if someone could recommend a good embedded board to get me started?

Cost is more of an issue than processing power, but I do need more flexibility than I get with a standard microcontroller. It also has to be small (about a foot square or less; the smaller the better) and lightweight (around 300g max).

The ability to plug in a monitor/mouse/keyboard isn't required, but it does have to interface with external (serial, 5V, 1kHz) hardware. Wireless Ethernet would be an advantage (but I could always hook it up to a radio transceiver).

It's going to be battery-powered and used in an enclosed space, so heat dissipation is an issue.

I'm sure I read somewhere that someone (Intel?) had managed to get an entire basic 386 motherboard/CPU onto a single chip that didn't even need a heatsink (but I can't find any reference to this on the web); something like that could be ideal.

[ EDIT: I have looked at lots of single-board computers out there but most seem to be too overspecified for my needs. I really do just want a processor, a few hundred kbs of non-volatile storage space for a program, some RAM, glue logic, and serial (& maybe wireless ethernet) I/O. I don't want to have to pay more for bells and whistles that just take up board space, generate heat, and won't get used. ]

Can anyone recommend such a board?

Thanks in advance,

— Robert J. Lee

Here is a link. No experience with any of their products.
http://www.embeddedx86.com/epc/ts5600-spec-h.php

Thank you; that looks like a pretty nice piece of kit. (Perhaps a little over-powered, but that's better than the opposite!) — and it comes with Linux pre-installed

I'll certainly consider that one. Anyone else have any suggestions?

There is a lot at http://www.icpamerica.com. There is more single board computers if you do a search.

I think you can get more information from http://www.linuxdevices.com/
It is a professional embedded linux system(hardware and software) web site.

also consider mini-itx.com they also have very small computer components etc you might be interested in.

not technicaly embedded though but more like today's computer specs

prices are about £90 upwards.