1) if you are worried with space, GUIDs have no place in your system.

2) why aren't you using NEWSEQUENTIALID??

3) Your PK on the parent does a clustered index on the NEWID, since you didn't specify one.

4) You are fragmenting the heck out of your nc indexes on those GUIDs.

5) Did I mention that GUIDs SUCK yet?!? Oh, and for multiple systems, you can almost ALWAYS come up with a simple multi-part numeric arrangement that is guaranteed to be unique across all systems. I have used a tiny/smallint ServerID and integer identity construct at numerous clients to eliminate GUIDS they "HAD to have", always with GREAT effect.