Yes, you are correct in that installing 1.7 then doing an upgrade to 1.8 would have to be a "last ditch effort"! I don't know if anyone has successfully pulled it off, without a serious amount of head-ache.
I would have to say, that maybe you should do a little research into your lap-tops and BIOS. There are quite a few manufactures out there that have specially built BIOS that will either "hide" setup options all together, or at least have an option that you need to change in order to even install a OS on it. I have a buddy with a Dell that had this exact problem. I found that by doing a little research I was able to get his computer to have a new OS installed on it.
-so long, long story short, look around on google and do some studying on your particular lap-tops and bios settings. You might find something.