Themes are applied  at the time that you create  or save the site. Subsequent
changes to the theme  are not reflected in your site  unless you reapply the
theme. This is different from site definitions, which are applied each time
you load the page.

A custom  Site Definition is NOT applied  each time you load a page. The
Site Definition is only used when you first provision the site. If you
go back and make changes to the ONET.xml it will only affect new sites.
If you referenced a custom master or cascading style sheet in the Site
Definition and make changes to those then the changes will take affect.

What about modifying the default.aspx for the site  definition? Same thing?
Admittedly, I didn't consider other files such as ONET.XML. I was referring
to WSS 2.0, BTW, as I haven't dealt much with MOSS2007. I don't know if that
makes a difference.

If the default.aspx file has been modified using sharepoint  Designer
then changing the one in the site  definition will have no effect. If
not, then the changes will take effect.

Once your privision the site, it will be created in database, and it will
maintain, its all resouces like, images, css, master page in DB only.

So for your scenario, customize the your master page and css files to match
your custom  theme, and select option  of inheriting parent site theme  while
creating sub-sites

During provisioning the master page and default.aspx are ghosted to the
DB, not actually copied. They won't be actually copied unless you
change them using SharePoint Designer. Until that happens you can
change the ones in the 12 hive and it will take effect.

Can you give me bit more info about inherting the
parent site theme  while creating sub sites? I did not get this option  while
creating the sub sites.

I thought the key difference between modifying site  definitions and site
templates were that changes to the site definition WOULD carry across to
existing sites  created using said site definition. Am I wrong here? I could've
sworn that I've read this several times before, but I've never actually gotten
around to enacting this kind of modification yet.

A site  Template is just a delta file (think of it as a macro) of the
differences between the original site definition and the current site
when you create  the site template. When you create a site from a site
definition it is provisioned based on the site definition. When you
provision a site from a site template it first creates the site based on
the original site definition and then applies the changes that you made
and recorded in the site template. Making changes to the Site Template
or the Site Definition will not change  the resulting site after it is
created. Making changes to files referenced by the site template or
site definition (like .css files or .master files) will change the
existing site.

I'm not sure where you thought you read differently, but the
misunderstanding may come from the fact that you can easily reference
external files like style sheets, master page files, etc from a site
definition. You can't really do it with a site template.

So, if I'm understanding you correctly then making changes to list definitions
suffer the same rules, correct? Is there any way to make widespread changes to
existing sites  or lists?

If you reference a Master page, a css file, a default.aspx file in a
site definition and leave it ghosted (ie. Don't edit it using SharePoint
Designer) then any changes those files in the 12 hive will be reflected
in all sites  that were created with that site  definition. And Yes, list
definitions are subject to the same rules.

OK, that's what I was referring to then. I understand that all bets are off
when it comes to unghosted pages.

I thought the key difference between modifying site  definitions and site
templates were that changes to the site definition WOULD carry across to
existing sites  created using said site definition. Am I wrong here? I could've
sworn that I've read this several times before, but I've never actually gotten
around to enacting this kind of modification yet.

If you are referring to MOSS07....

What sort of changes did you make in your theme?

If you change  a theme, or a part of the theme, there is a process you
need to follow in order to see your changes. Even if you change a
font color in a style sheet or an image.

After you make a change you need to recycle the Application Pool in
IIS on the server.

Next, go to the site  Settings through your Site Actions button. Apply
a different theme  to your site other than your custom  theme, then
repeat the process and reapply your custom theme.

Last, delete your browser temporary internet files including offline
content, and refresh your page. You should see your changes.

I know this sounds like a witches brew. At times, depending on the
type of changes you may not need to do every step, but for the more
subtle changes, you will find it works best with the "brew".

Another "feature" of Sharepoint!

How about in the Master pages? If a particular theme  has to be
applied across all collections and sites  in a farm, wouldn't it be a
better idea to modify the Global Master page? Just curious, that way
the changes would be immediate aross all sites without having to do
anything else?

Changing the Master Page will not impact the theme. If you do not
apply a specific theme  to a site, the default  theme will be applied
automatically.

The colors, fonts, images are controlled by the site  theme and not the
master page. Once you have built the master page and applied  a theme -
either custom  or an out-of-the-box theme, then you can set your child
sites to inherit the theme and masterpage from the parent.

Basing on the discussion till now on this topic, I believe having a custom
theme is the best way to do the Farm level style changes.

But, the difficulty is in getting the changes reapplied, which is to be done
through
1. IIS Application Recycle
2. change  the theme  of the top level site  to a new one and reset it back to
the current one
3. Clear the browser cache

Does the step 2. needs to be done for each top level site in all the site
collections? Any ideas why this step needs to be done? Is this because
Sharepoint is copying the Theme information from the file in 12 hive to the
database?

The other option  that was suggested is to attach a CSS file to the master
page, which probably is more simpler. But, I am doing the changes not to the
default theme  but to another delivered theme from Sharepoint. So, anyway I need
a theme, other than default, to be applied  for all my site  collections of the
Farm.