"data at rest"

would anyone out there like to share what they are doing to secure
data at rest? with more and more of our customers asking about it, we
are exploring two solutions and probably will implement both -
encrypting the database file on disk and encrypting sensitive data
before inserting into the database. i am interested in what others are
doing with the latter. our issue is that the sensitive data is data
that needs to be searched on and possibly diplayed on the web. we are
considering two approaches. the first is storing both a one-way
encryption/hash on the data to enable searching and a masked version
of the original data for display (i.e. 12XXXXXX34). this way we never
store the original data in the db. the drawback is that we can't
recover the original data, which might be needed for other processing.
the second approach would be to store both a hash of the original data
for searching and two-way encrypted data, which would allow us to
decrypt the original data if needed, but will also be expensive (our
app is high-volume) and we'll need to consider how to securely store
the keys. any input is appreciated...

thanks,

eric