CHARINDEX And STUFF/REPLACE

Hello,

I need to be able to replace only the first occurance of a space character
in a column.
Reason being is the data in the column I am trying to replace seems to have
umpteen space characters after each entry, so a simple replace function
will replace all the spaces after it with what I want!

I have thought of RTRIM to get rid of the spaces after and then replace, I
have also thought of CHARINDEX to find the first occurance of a space and
STUFF to replace it.
I have done my homework on these functions!
But I am having trouble writing such a statement,
I've never written a query which would use more then one function on one
column you see and I am getting confused!

I'll tell you what I want to do in simple steps

Replace only the first found space in a name column, but then if a name has
a middle initial that will be a problem,
Replace that with a dot.
then concatanate '@emailaddress;@emailaddress2' after it
so when SQLServer does the select it will bring back something like

joe.bloggs@emailaddress;emailaddress
But I guess I'd also need joe.n.bloggs@emailaddress;emailaddress

The data in the column looks like this at the moment

joe bloggs
But I guess there may come a time when we have
joe n bloggs, just to complicate things!

What is your advice, and how do I write a query like this
I have been playing around with it in Query Analyser but as I said I am
getting confused and need some help if you don't mind

Thanks a lot to all who reply :-)

Regards

Jayne