Today I needed to install CentOS 5.1 on a server to try out OpenVZ and I didn't feel like downloading 6 CDs or 1 DVD. That screams bloated crap. So, I searched around the CentOS mirrors and found a file named CentOS-5.1-x86_64-netinstall.iso. Looks good but to make sure I searched on google and found on CentOS-announce that 5.1 is the first version to have a netinstall iso.

Getting the ISO
If you have i386 (ouch, that sucks): http://isoredirect.centos.org/centos/5/isos/i386/
If you have x86_64: http://isoredirect.centos.org/centos/5/isos/x86_64/

Pick a mirror, then pick the CentOS-5.1-<arch>-netinstall.iso file. Notice that the file is only 7.5MB. Much nicer.

Installation Method
When you boot from the net install CD it asks for country/language and then the Installation Method. Here's where you should pick HTTP.

HTTP Setup
Here it asks for a specific mirror and directory to download from. I was expecting it to display a list of mirrors but whatever. I used singlehop's mirror and this is how it's entered:

Web site name: yum.singlehop.com
CentOS directory: CentOS/5.1/os/x86_64

The instructions don't tell you but the first file it tries to load is <Web site name>/<CentOS directory>/images/stage2.img so you can use this to figure out the correct path for your mirror.

Further recommendations:
If you're installing a server like me, review the actual packages that are getting installed. I picked the Server setup and found a bunch of useless crap like dialup networking support, wifi support, and pcmcia support marked for install. I think the CentOS (RHEL?) team should review what they believe a server these days should contain.

If you plan on installing multiple servers in your organization this way, you should setup a local repository.