Here I am, after slotting in the new 160GB hard drive and downloaded FreeBSD 8.1.
This time it boots well, so well that I am now typing on firefox on KDE on Xorg on FreeBSD8.1
Although I am still configuring my Samba share, but to my delight, my data in ZFS can be ported to FreeBSD without much issues.
Once everything is well and smooth. I will install FreeBSD to my 500GB OpenSolaris drive, and wave OS good bye.
So be it, after 3 years. At least I still have my ZFS. :)