A friend of mine had a Toshiba Satellite laptop (Came with Windows Vista) and we took it apart because every time we installed ( Linux Mint, Debian, Crunchbang or any other distro for that matter) all we saw was a black screen or a flashing cursor:-
We took the laptop apart and cleaned the heat sink. The fan was pretty nasty so he replaced that too.
After we re essembled the laptop I tried installing Linux Mint Debian, Crunchbang and Voyager 12.04, the only distro I could get to run on that laptop was Puppy Linux-
Voyager 12.04 would boot and the system would remain up for about 10 seconds and than the DE would repeatedly 'lock up'
We also tried wiping the HDD that didn't work. My friend even purchased a brand new HDD and still the same results.
He purchased brand new RAM and that made no difference either.
Till this day I still don't know what was wrong with that laptop but if I had to guess I think the graphics card may have been on it's way out. Aside from that I found a few articles were folks were complaining that some of the Toshiba's are notorious for overheating-
My friend thinks that the Windows update he allowed wrecked the microcode. BTW the laptop was fine before the update.
Shame you don't have a distro installed alongside your Win's 7 OS because you could use it to verify the integrity of the iso image before you proceed.
I don't want to just wipe Windows off the drive and load something I haven't demo'd in the laptop.
I know you said that you don't want to partition the drive but that's one way.
You could dual boot the Win's OS that's one that Toshiba and Linux.
Not sure what the name of the application is to shrink Windows Vista; sorry-
Using the application "G-parted" is how you would create 2 partitions for you Linux install.
I'll help you if your interested-