If you're going ahead with this, some tips for ya as I can't sleep with all this jet lag.
(1) If you run Windows, get XAMPP (
http://www.apachefriends.org) or WAMPserver (
http://www.en.wampserver.com). If you're on a Mac, get MAMP (
http://www.mamp.info). I've never used MAMP, so I don't know how realistic a testbed it is.
(2) If you can't set up your own server with old computer parts, don't bother buying hosting yet.
(3) Learn PHP (preferably PHP5, but PHP4 should be fine as well) and MySQL. Buy a book, program, and most importantly, learn by example. It REALLY helps.
(4) ALWAYS use php.net if you're ever stuck on anything. It's a great site, it's got lots of examples and it's extremely easy to use. Example: if you forget how mysql_fetch_array() works, no need to search on Google - just head right on over to
http://php.net/mysql_fetch_array/ .
(5) If you're going to get hosting, make sure you know (a) what the hosting provider gives you, and (b) what contract you'll be under. It's kinda like getting a cell phone contract, except with alot more perks
Oh, and read reviews about that host...make sure they are reliable, safe and fast.
(6) Don't expect 1,000 members right away. Don't even expect 100.
(7) I can't stress this enough. ENCRYPT PASSWORDS. You don't even need two-way encryption for passwords. Just use a one-way hash like sha1("your text here"), since with passwords all you're doing is comparisons. You never need to know your members' passwords - you can always CHANGE them, but you don't need to READ them. Google SHA1 or MD5 if you want to know more.
(
If you're going to use a web application framework, write your own. Most out there are tailored for big applications, but games are a whole different world, since you have so much user interaction.
(9) Make it IE friendly too. That means using IE stylesheets, <!--[if IE] statements, and whatnot. However much you want users to use Firefox, IE still unfortunately rules the population. Still.
(10) Use CSS, and if you do declare yourself XHTML-whatever valid, make sure it is. Googlebots search better than way.
I know there's a lot there, so don't be scared about all of it - web development is really fun and enjoyable once you get the hang of it
Feel free to reply or PM me if you want to know more. And for those of you who know what I'm talking about, feel free to reject anything I've just mentioned
