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

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

I have a new Dell server with no OS installed. And 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.

From serverfault

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

  mh : That's what I'd do. Chances are you're going to need that external drive again sometime, and it's not like they're hideously expensive anyway.

  John Gardeniers : This should be on every admin's "must have" list.
  From joeqwerty

• 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.

  From EJB

• use unattended (http://unattended.sourceforge.net/) or RIS from Microsoft. We install all systems (windows/linux) from pxe and you know that they are all installed the way you wanted them to.

  Sure, it costs you more to do it the first times, but these is one of the things that when you implement then you say to yoursel: why didn't we do this before?

  From natxo asenjo