upgrade advice & question

Hi,

I use both D7 and BDS2006 on different machines.

Now I'm considering upgrading to RAD2007 via BDS2006 and
not D7.

Before I purchase anything I was wondering about the issue
of installing an upgrade.  Does the previous edition *have*
to be installed before I can upgrade, or can I just
use the CD of the previous version?   This is particularly
important since I might be upgrading my system next and
I *really* do not want to install BDS2006 update 1 & 2
and then install the RAD2007 upgrade.  I'd prefer to
go directly to RAD2007 and have it ask for BDS2006's disks.

Secondly, is upgrading from BDS2006 to RAD2007 *that*
difficult?  While I don't have any 3rd party components
installed (if you don't include those that come with BDS),
I have my own component.  Since RAD2007 purports to support
BDS2006's components off the bat,  should I take that
with a grain of salt, or does it really do what it says it does?

Any clarifications appreciated.