Wubi gives me errors when installing and I don't have a disk drive, so I was wondering if I could mount the ISO to the hard drive. Is there a tool for doing that, and would I encounter any problems, like missing Grub boot manager? If I was missing it, how would I install it? Would there be any other things to install?
SnapOverflow
In some cases it's just the .iso file that is corrupted, then all you need to do is to download Lubuntu again.
Assuming or case isn't the above, First thing, no you don't need to install any other thing. Second, you can mount Lubuntu .iso, although it will be of no use. Wubi isn't the best way of installing Lubuntu (in my point of view it's the worst), you should try installing it in dual boot with Windows, it's just to burn this .iso to a CD/DVD or USB and boot your pc trhough it, then you should choose 'Try Lubuntu without installing', wait to the interface to load and from there you will be able to open GParted and create a partition for Lubuntu after Windows partition, then you just need to install Lubuntu and when prompted choose advanced options to choose the partition you created to Lubuntu and to keep Windows in your pc.
If you need, for any reason to use wubi for the installation process you should defragment your disk data, make sure you have at least 3 GB of free space in your disk, update your Windows' softwares, it's recommended that you close any running program in Windows during the installation process, after doing these steps you should be able to install Lubuntu trhough Wubi, although if you don't succed you won't be able to do many things as something into Windows or HDD (such as badblocks) are hampering Wubi performance and preventing the installation of Lubuntu.
You will have to research more on step five because it's a Gentoo tutorial (dont see Ubuntu tutorial) but fundamentally similiar concepts most likely needing modifcation to achieve success. This either will be a learning experience or you may just want to find a easier way.