How to install windows on a server with no CD or DVD drive

I've found a few posts on this site, however my situation is different.

I have a new Dell server with no OS installed. I would like to install Windows 2008 Web Edition. I have a few USB ports and Ethernet. No CD or DVD drives.

Is this article the best & only way to proceed? Installing Windows 2008 via USB thumbdrive or should I just get a external hardrive and hook it up to a usb. Once the OS is installed I'll never need a DVD drive again - so that's idea is a waste of money.

I installed windows 7 via a bootable thumbdrive...really easy to do, and I assume windows 2008 would be about the same effort. It is not something that you need to do everyday for this server, so you really don't need the "best way", just anyway that works.

Why not just connect a USB CD\DVD drive and install from there?