Win7 won't install on a 2010 MacMini SL w/no optical drive, crashes when accessing external HD

I've been trying to install win7 on my Mac Mini with 10.6.8 that doesn't have an optical drive. I've been able to do the bootcamp partition just fine but when it goes to restart into the windows partition with the win7 disk in the external HD, my screen goes grey, then a green with purple border and then black. I have to reboot and if I press the alt/opt key, I'm able to get into OSX again. The research I've done shows I need to create a .iso file which I did with disk utility. I created all types of .iso files, read only, compressed and dvd.cdr files. Nothing is working. Bootcamp is not recognizing any of the 5 thumb drives I've put the .iso files on as I read some drives aren't able to be recognized. The external HD works as I reinstalled SL just fine using it. My research also shows that win7 won't install from an external HD. So I'm at a a loss as to how to proceed from here. I went into my old windows machine to try to create a bootable thumb drive after I install win7 there but the Dell is so old, I don't have a DVD drive in it, only a CD drive. And if I buy a downloadable version of win7 I still need to get it to a DVD or a thumb drive to get it installed.

Does anyone have any ideas? I called Apple and their support ended at "well, we did our job by getting you to the BootCamp partition" which is a crock. It's their design to take out the optical drive and now it's everyone else's problem! Sorry, I know I've got attitude but I'm so frustrated!!

Thanks in advance! I'm posting this here and in mac mini discussion.