No-ip.com has free DNS fowarding with Linux support, so you're covered there. Mail serving is a bit, well, interesting, but there are plenty of great tutorials out there on setting one up under Linux.
Slackware 9 is a great choice (what I use). Debian is supposed to be easier to maitain, but all my experience with it has been quite negative. My system specs are similar to yours, and works just fine. The nVidia card is fully supported, BTW.
There are plenty of open-source mail servers avaliable. You'll need two kinds, STMP and POP. STMP is what you use to send main back and foward between servers, and POP is what is used to store mail for the computers that are to be accessing this server.
Places to go for mail server info:
http://www.sendmail.org/ <- an SMTP server
http://www.yolinux.com/TUTORIALS/ <Scroll down to the e-mail section
http://linux.oreillynet.com/pub/a/li...il_server.html http://linux.oreillynet.com/pub/a/li...l_server2.html
-edit-
You won't be able to
play any of those games in Linux (regardless of Distro or whether or not WineX is used). You will be able to set up servers for most of them on a Linux box.
BF1942 Linux server:
http://www.3dgamers.com/games/battlefield1942/#filelist
/\ Under Official Files
Day of Defeat Linux server:
http://downloads.gameplanet.co.nz/dl...iles/3203.html
Soldier of Fortune II Linux Server:
http://www.3dgamers.com/games/soldierfortune2/
/\ Also under official files
Halo Linux server not availiabe to my knowledge.
-edit- I take back what I said about not being able to play the games. Day of Defeat will work okay under WINE, but don't expect it to be perfect.
-one more edit - Oh, and I should point out Slackware is harder to use than SuSE, but can be much more functional.