One Bad Omen

Ok, so i have a table that has a primary key that also serves as an auto_increment, so every user has their own unique #. Well how would I get that # in the url? like lets say www.mysite.com/user=# and then it would take you to that users page?

For my website I upload it using SmartFTP 2.0, well yesterday my comp got a virus and I can barely get it to start up. In order to fix it I may have to dump everything, I don't know yet though. My question is will all of my information be lost or when I redownload FTP and connect to my host will the info be in there?

Hi, I've got my forms working and it goes into the database all fine but I don't know how to make it where they can only enter a-z, 0-9 and spaces. Anybody know of a simple way to validate a form with these conditions? I'm already using the mysql_real_escape_string() and strip_tags() for security but it doesn't stop people from puting in other things like *,$,!., and so on. Any help will be greatly appriciated!

Yes but I also noticed that there are some things in the php tutitorial that has xml in it. So would it be more beneficial to know xml and php rather than just php?

I currently know html, xhtml, css, and javascript. I plan on learning php but I don't know if I should learn xml and xsl first or if it will be usefull for php. Thanks for any help and advice.