I doubt you would be able to create a disk image on the PC and move it to the iMac. Good thought though. Apple will send you the CD version of iLife, if you ask. You cannot use iDVD as you have no DVD burner so the whole thing will fit on a CD (or two). You could ask about iWork while you are there.
You could try: Insert the DVD into the PC, copy the contents to a folder, move the folder to the Mac and run the installer from there. It "might" work.
I have a nagging thought that there is a way to install if you do not have a DVD player but I cannot put my finger on it right now. Bear in mind that with your processing power, you will be limited to iTunes, iPhoto and iMovie. There will also be restrictions on the type of editing you can do in iPhoto. You also fall below the minimums for iWork. It will work but it will be slow(ish)
Call the Apple store and ask about the CD option.

P