David Woolley wrote:
[...]

The minimal footprint is probably
using a hand customised Linux system.  It may be possible to shoe horn this
into 16MB without too much disk thrashing (the client working set is
about 13MB), 20MB should definitely be achievable, and 24MB ought to be
possible without too much skill, and should easily allow a diskless
implementation, if you have the skill.

This sort of thing has already been done and is freely available.

eg:

Mini PC Linux - a distribution of the Linux kernel and some utilities which comprise a usable operating system suitable for processing workunits
http://www.myurl.net/seti/minipc.htm


Run SETI@home on Linux without a hard disk.
http://lrp.gibbsoft.com/


LRP SETI Boot Disk Information.
LRP (Linux Router Project) SETI boot disk page. ... After the disk boots type root at the Logon: prompt. ... now and press ENTER or just reset the computer. Linux should boot and download a work unit. ...
http://bhs.broo.k12.wv.us/homepage/staff/seti/lrp-seti.htm



Regards,
Martin