Some questions about installing a web server.

[刘伟南]

Hi guys,

I'm a freshman man here. Please do not mind my silly questions.

I am ready to install a web server, the main hardwares are as follows:
CPU 4-core xeon 5410 * 2
MEM kingston 2G EEC FBD667 * 2
HD ST146G SAS 15K * 1

I have several questions.
Which platform should I chooses? amd64 or i386?
Is 4G memory enough for 2000 people online?

If you have others suggestions please tell me.
Thanks in advance.

Vivian