I would recommend you to use free software Phototheca for Windows (I participated in creation of this app) to organize your photos in the same way as in iPhoto.
In Phototheca you can import all your photos and it will create events automatically basing on time stamp of photo (exactly as iPhoto does) and later you are able to merge or split events as you wish to organize them.
In your case I guess you may import whole folder 'My Pictures' into this app and most of your events should pop up automatically (of course some adjustments may be required later).
My experience is that I imported near 10,000 my photos with lot of events and can say it handles them very well, no hangs or slowdown, just works.
Below is a screenshot: