Equivalent of ScanDisk???

[Subscriber]

I have Samsung Spinpoint 160Gb drive which is a few months
old. It has some bad blocks - presumably from day one.

It has a 3 year guarantee so I could return it but it would be
tricky to get the 70 Gb or so of data off it, especially as it is
in a machine which can only take one hard drive (an Asus
Terminator).

Is there any way in FreeBSD of mapping out the bad blocks
or otherwise making them inaccessible? Even something like
creating a file over those specific blocks then making it 
immutable would be OK.

jim