Running VirtualBox VM host on ReadyNAS Pro

Trying to follow this through on my ReadyNAS Ultra 4 (RAIDiator 4.2.17). Hopefully not trying to be too clever for myself, instead of doing the following:

# wget -q http://www.readynas.com/download/GPL/RNDP6xxx_4.2.4_WW_src.zip
# unzip -q RNDP6xxx_4.2.4_WW_src.zip -d ./GPL

I downloaded RNDP6xxx_4.2.17_WW_src.zip instead, assuming it matched my RAIDiator version and it was the right thing to do. Trouble came when I tried to unzip it. The first half of the unzip looked like it was going well (I didn't use the "quiet" option so I could keep an eye on it), but then it started giving errors around the packages that started with "l":

checkdir error:  cannot create ./GPL/libidn-0.6.5
                 unable to process libidn-0.6.5/java/gnu/inet/encoding/CombiningClass.java.
checkdir error:  cannot create ./GPL/libidn-0.6.5
                 unable to process libidn-0.6.5/java/gnu/inet/encoding/Composition.java.
checkdir error:  cannot create ./GPL/libidn-0.6.5
                 unable to process libidn-0.6.5/java/gnu/inet/encoding/DecompositionKeys.java.
checkdir error:  cannot create ./GPL/libidn-0.6.5
                 unable to process libidn-0.6.5/java/gnu/inet/encoding/DecompositionMappings.java.

As a consequence, the

# cd GPL/linux-x86-2.6/

dir didn't exist and can't do that step. Any ideas what's going on? Here is the dir listing of what did extract successfully so far:

# ls GPL/
acl-2.2.47                               findutils-4.2.28
acpid-1.0.4                              flac-1.2.1
adduser-3.112+nmu2                       freetype-2.2.1
apache2-2.2.6                            gcc-4.1-4.1.2
apr-1.2.7                                gcc-4.3-4.3.2
apr-util-1.2.7+dfsg                      gdbm-1.8.3
apt-0.6.46.4                             gdisk-0.6.13
at-3.1.10.2.netgear1                     glibc-2.7
attr-2.4.43                              gnupg-1.4.9
avahi-0.6.23                             gnutls26-2.8.6
base-files-4.0.1~bpo40+1                 gphoto2-2.2.0
base-passwd-3.5.11                       grep-2.5.1.ds2
bash-3.1dfsg                             gsasl-0.2.26
busybox-1.18.4                           gzip-1.3.12
bvi-1.3.2                                hdparm-9.32
bzip2-1.0.3                              host-20000331
coreutils-5.97                           hostname-3.04
cpio-2.6                                 ifplugd-0.28
cracklib2-2.7                            ifupdown-0.6.8
cron-3.0pl1                              iptables-1.4.8
cupsys-1.1.14                            iputils-20020927
curl-7.19.7                              ipwatchd-1.2
cyrus-sasl2-2.1.23.dfsg1                 iscsitarget-1.4.20.2+svn396
db3-3.2.9+dfsg                           isns-2.1-01+dfsg
db4.4-4.4.20                             kernel-build-tools-x86
db4.8-4.8.30                             keyutils-1.2
dbus-1.2.1                               krb5-1.6.dfsg.4~beta1
ddrescue-1.10                            libapache2-mod-auth-pam-1.1.1
debconf-1.5.36.1                         libapache2-mod-perl2-2.0.2
debian-archive-keyring-2007.07.31~etch1  libapreq2-2.08
debian-backports-keyring-2007.06.10      libcap-1.10
debianutils-2.17                         libcsv-3.0.0
devmapper-1.02.08                        libdaemon-0.12
diffutils-3.0                            libdbd-mysql-perl-3.0008
dosfstools-3.0.9                         libdbi-perl-1.53
dpkg-1.13.25                             libdevel-symdump-perl-2.03
dropbear-0.52                            libdvdread-0.9.7
dtach-0.7                                libedit-2.9.cvs.20050518
e2fsprogs-1.41.14                        libevent-1.1a
e2fsprogs-git.master.20110209            libexif-0.6.16
ethtool-6+20080913                       libfile-ncopy-perl-0.34
exim-3.36                                libfile-remove-perl-0.31
expat-1.95.8                             libgcrypt11-1.4.5
faad2-2.6.1                              libgd2-2.0.33
ffmpeg-0.6.1                             libgpg-error-1.6
ffmpeg-0.6.1.tgz                         libgphoto2-2.2.1
file-4.17

In addition to the above, instead of installing VirtualBox 3.1 I found some Etch packages at http://download.virtualbox.org/virtualbox/3.2.8/ so was going to follow the above but use that instead. No problems envisaged with that?