Switching Files and Domains

I need some assistance.  Right now, I'm working on 2 sites simultaneously.  Site A is under Domain A and Site B is under Domain B.  Both of these site are starters and inactive.  Last night, I realized that Site A would work better under Domain B, and Site B would work better under Domain A.  Today, I been messing around trying to switch the files, but I'm having no luck seeing both sites online under the switched domains names.  This is what I did so far.

1.  Moved Site A files in Domain B folder, and moved Site B in Domain A folder

2.  Transferred both folders onto server. 

3.  Changed header info on both.

What's next?  What am I missing?  For someone doing what I'm doing, what's the proper procedure?  If any.

Thanks,

Craig 

I am not sure what all is involved, but just wanted to point out that if you are using a different database for each site/domain, then you may need to rename them

DB was changed...included in changing header.inc info

and what exactly problems do you have?

Well...for 1, that parse error popped up on Site B.  Also, when I type in the domain for Site A...I get redirected to Site B (where I saw the error).  So...I can't even get to Site A at all.  All the header files for both sites have been changed...am I missing something?

Before:

Site A files  - Site A Domain

Site B files - Site B Domain

Trying to do:

Site A files - Site B Domain

Site B files - Site A Domain

Result:

key in www.sitea.com, I get www.siteb.com (parse error)

can you give us a links to check it up