As far as I know that is all that will cause it. You can check in your BIOS for the boot order settings, just make sure your hard drive is listed as the first device to boot from, but it really shouldn't make any difference.
Also, I'm pretty sure Microsoft lets you download the Windows image + a program that will put it on a USB stick, you just need to provide your Windows Key.
Try reading this.
http://www.microsoftstore.com/store/msstore/html/pbPage.Help_Win7_usbdvd_dwnTool
It will require a 4GB memory stick though, just fyi