Hello,
The BOINC client reports an odd amount of system memory on Debian GNU/kFreeBSD - this was recently reported in Debian's BTS, please see http://bugs.debian.org/456586 for more details. The submitter kindly attached a patch to fix this issue for him and I'm attaching it to this ticket for your convenience. Note that I didn't had the time to review or test this patch.
Debian GNU/kFreeBSD is different from traditional FreeBSD because it consists of GNU userland using the GNU C library on top of FreeBSD's kernel, coupled with the regular Debian package set.
Thanks,
Frank