IMPORTANT!
While looking for a bit of recovery software try to use your PC as little as possible and do not turn it off.
Saving files to the drive your images were on could be very bad news! Switchin of the PC will mean status info gets saved.
Ideally search for a solution usings another PC.
As BOAC said windows does not delete files, it marks the space they occupy as usable. As well and meaning the files can be recovered it also means that if you allow stuff to be saved to disk, including tempoary internet files you risk overwriting some or all of the files, or perhaps more annoyingly, parts of them which will render them corrupt when they are recovered.
If you are on windows XP try the recycle bin - expect you would already have tried this if you have it!
If the files were on removabal media - e.g. a memory card there are special tools to recover and repair files I expect recover and flash memory could be good search terms.