select for update

I'm pretty new to databases in general, and would like to find a spiffy 
way to do something. I want to use two columns from one table to 
populate three columns in two other tables. Assuming t1 is the table I 
want to take the values from, here is the structure of what I want to 
insert into t2 and t3.

t2.id = t1.id
t2.groupname = t1.username
t2.owner = t1.username

t3.id = <next available>
t3.groupid = t1.id
t3.username = t1.username
t3.writeperms = 31

PS - I'm not subscribed to the list, so please CC my email with responses.

-- 
; Justin Georgeson
; http://www.lopht.net
; mailto:jgeorgeson@lopht.net
; "Free the mallocs, delete the news"