Laptop

Help please. I've got a Dell Inspiron 1545 the other day a virus attacked my laptop but i reformatted it and i got a friend to reload windows vista on, now it says I've got my DRIVE (C:) and my OS (D:) the other way round which it should not be a mate had a programe to changed it around but he forgot how to use it. i should have 14.6GB in my OS (D:) and in my DRIVE (C:) i should have at least 283GB in it. should i reformat it again and load Vista on it. and also it say's Windows cannot find any networks my computer has a wireless network in it so i don't need to the internet cord for it. it also say's windows did not detect any wireless network hardware at all please help so i don't have to spend money. Thanks Gerva