PHP and cookies and/or headers

Greetings, Is anyone REALLY familiar with PHP and cookies and/or headers-- I have a tough nut to crack and it involves three URLs. Here is the situation, and I really want to avoid using our DB if I can. I have a main URL that everyone will probably hit - splash page. www.mainurl.com From there, users go into either the french or english version of the site with two unique URLs... www.english.com www.francais.com I want it so that if users go back to the splash page, it will pick up their language preference (french or english) and send them to the index page of either www.english.com or www.francais.com -- depending upon the last argument set when they were last at the site. So, if they ended on an english page, they would start at the english index page, but if the finished on a french page, they would start on the french index page. The problem with cookies is the fixed URL from which they can be read. Obviously www.mainurl.com cannot read a cookie set by www.francais.com -- so how can I over come this. I suppose I could do it via IP stored in a DB, but even then there is a problem as people who hide behind one IP -- say a large business -- would be stuck using each others' preferences depending upon who used the site last. I also do not want the user to have to type in a code word so that the IP is tagged with a special identifier. I suppose I could use a random number generated from a time stamp... but I really want to avoid using a DB! -- mostly for speed and bloat of page size reasons. Thanks in advance! Jeremy