Large table search question

Guys,

I have a general question about designing databases for large data sets.

I was speaking with a colleague about an application we're preparing to
build.  One of the application's tables will potentially contain 2 million
or more names, containing (at least) the fields first_name, last_name,
middle_name and prefix.

A common lookup the application will require is the full name, so prefix +
first_name + middle_name + last_name.

My friend's suggestion was to create a "lookup field" in the table itself,
which would contain a concatenation of these fields created during insert.
 So, for each record, we'd having each individual field and then a
full_name field that would contain the combination of the ind. fields.
His argument is that this will make lookups in this manner extremely fast
and efficient.

I agree with his assertion, but get the feeling that this is sort of an
ugly design.  Would a compound index on these fields really be less
efficient?

Thanks for your help!

John