Options to move from sms 2003 to sccm 2007

I am looking at the different options for moving from SMS 2003 to SCCM 2007.

Here is our set up

SMS 2003
Latest SP
Advanced Security
runs off SQL 2000
only has 1 site

SMS 2003
150 odd Packages
150 odd advertisements
100 odd collections
900 clients

SQL 2000 (On a different server to SMS)
This server cannot be upgraded, however the database can be moved to SQL 2005 if need be.

Now I want to know the different options in moving to the new version, and what the pros/cons are of that option.

Eg. So looking at these sorts of scenarios.
Scenario1
Move SMS 2003 SQL database to SQL 2005
Move SMS 2003 to new server
do an inplace upgrade to SCCM 2007

Scenario2
Move SMS 2003 SQL database to SQL 2005
Build a SCCM Server from scratch
set SMS 2003 server as child site
once things are replicated remove child.

scenario 3
Build a SCCM Server from scratch
Create each package/Advertisement/collection manually.

so any options on migrating, why its a good/bad option. how easy is it to move clients from 1 server to the next(upgrading the client and stuff). And any resources I should be looking at, doccos and stuff.

keeping history on the clients is not a requirement, however if you think thats a PRO add it.

if you are unclear about anything please let me know. Thanks