Downloaded software disappeared and won't be overwritten!

I have a relatively new PC as I lost everything on the old laptop. Tonight, I am trying to transfer pics from my camera; I thought I had previously downloaded the relevant software from the Fuji site, but couldn't find it. I went back and downloaded it again, but when it goes to install it says the file is already "in use" and can't overwrite it!
So not only can I not find what I seem to have downloaded before, but I can't start again!
I am dying of frustration - I MUST get these pics onto the PC urgently, I even found the right cables now there seems to be a software problem..... could it be that the software is not Vista compatible?
Any advice appreciated.